It is kinda neat, but OpenSCAD's limitations are the main thing that motivated me to write this Python library to generate 3D meshes used signed distance functions:
Could you please elaborate on how this is different than the other python based modeling tools - build123d[0] and CadQuery[1].
I recently also got annoyed with OpenSCAD and its limitations and therefore started experimenting with Build123d. I'm very much a beginner in the CAD space and would love to understand what inspired you to build sdf.
My basic understanding is that STL files are essentially like Bitmap images and store a list of triangles and their positions, whereas STEP files are more like Vector art where there is a list of instructions on how to build the model. Most CAD GUI programs also operate on a similar model to vector art where they record a list of operations one on top of another. It's why STEP files are a standardized format and can be imported / exported from most GUI based CAD builders. I think.
Given that SDF also seems like it builds only STL files (I could be wrong), wouldn't learning build123d or CadQuery work better if one cares about compatibility with existing GUI based CAD modeling software?
Additionally, atleast build123d offers a similar conceptual model to using Fusion360 and FreeCad - I have limited experience here - but essentially you sketch something in 2D on a particular plane, and then apply some operations to convert it to 3d in a particular manner - the simplest being extruding. This means the mental modeling of how to construct something is very similar across both GUI based CAD programs and Build123d, and that makes it easier for me to jump between GUI based and code based CAD modelling.
I'd love to understand your point of view, and learn more.
> You can even load an existing 3D mesh and operate on it as an SDF. Great for hollowing, chopping, eroding/dilating, etc. existing models.
This has my instant interest. Multiple times I have wanted to take an existing .STL file and cut a hole on it or add another object to it and have never had success.
I've tried things like Meshlab, but while the interface has what appears to be a hundred different functions, attempting to use anything returns some error code that requires a PhD to understand and none of the "repair" functions seem to help.
I mean seriously: Mesh inputs must induce a piecewise constant winding number field.
How the hell am I supposed to accomplish that on a STL file?
That feature requires getting pyopenvdb installed, which can be a headache, and I never really updated the README with examples, but it does work. There is one example script:
Blender also has a high learning curve but you typically don't need a PhD to understand the errors (instead you just watch youtube videos and copy what they do).
Removing faces from an STL and adding other objects is quite straightforward. Previously, Autodesk had Meshmixer and 123D, I guess Meshmixer is still available: https://meshmixer.org/ and I found it to be great for quick editing of the type you're describing.
Just started using OpenSCAD recently and love it. While most CAD tools have a million features to learn, OpenSCAD is completely described by a cheat sheet you could print on a piece of A4 (like most programming languages).
I would really recommend using the git master than the latest release though. The last release was 2021 but they are still actively working on it and it's much faster now.
I also have to recommend the BOSL2 library which means you don't have to implement all of those one million features from typical CAD software yourself. Its definitely got a bit of a learning curve but the fact that you can always default back to vanilla OpenSCAD and that you can actually see how stuff is implemented makes it much more satisfying to me to learn than learning what all the traditional CAD GUI buttons do.
Commenting off of you since I wrote all of this and then realized it's basically exactly what you're saying. But to +1 everything you just said in my own words:
I love OpenSCAD. I've been 3D printing for a while, but I never really got to a place where I could design interesting parts until I started to get the precision of doing models in code. Sometimes it is slower, for sure.
Every time I've used as a CAD GUI program I would get to this point where I would need to alter a single dimension by 0.25mm and realize that _all_ of my fastener holes, cutouts, etc have to be nudged with the keyboard or mouse to accommodate it. The input devices lack precision for that kind of task, and having to repeat the operation dozens of times (or bulk select) gave me a terrible sinking feeling, and I'd often just step away and give up on the design at that point out of frustration. I try to approach everything in OpensSCAD in a way that means I never have to experience that feeling again.
I will also say that doing everything from scratch in OpenSCAD would be it's own special kind of hell. Libraries like [BOSL2](https://github.com/BelfrySCAD/BOSL2) provide a good set of core ideas and preferences that help set you on a good path. A good example: BOSL2 shapes tend to have a "center origin" by default, which is different than the OpenSCAD default, but makes doing transforms later way easier.
Anyway, happy to see OpenSCAD getting some attention here :)
> Every time I've used as a CAD GUI program I would get to this point where I would need to alter a single dimension by 0.25mm and realize that _all_ of my fastener holes, cutouts, etc have to be nudged with the keyboard or mouse to accommodate it.
There seems to be some fundamental misunderstanding of CAD here. I can't imagine how you could even design something in CAD in a way that you would end up in this situation.
I wonder if he's using TinkerCAD or something similar? I often use that, 'cos it's quick for simple things that are one-offs, but it has exactly this issue as it's not at all parametric, just primitives and booleans (though it does have some basic sketch capabilities now)
When I'm doing something more sophisticated I use SolveSpace, but I'm a lot slower with that.
yeah, op here: it's exactly that. I've used most of the free or open source software options and it seemed like none of them are parametric. I know I could buy fusion or something like that, but I found OpenSCAD before I got to that point and feel like it fits the bill for me.
>Every time I've used as a CAD GUI program I would get to this point where I would need to alter a single dimension by 0.25mm and realize that _all_ of my fastener holes, cutouts, etc have to be nudged with the keyboard or mouse to accommodate it.
What.
This makes no sense. This isn't PowerPoint; your holes and cutouts are supposed to be parameterized. How are they even supposed to be at the proper position in the first place?
As a CAD user, this is like e.g. a coder seeing someone write code with global variables everywhere.
I think I'm realizing that openscad was probably just the first time that parametric design options were given to me in a context where it made sense to me (in code). Maybe some of the software I've used has supported parametric positioning, but it wasn't made obvious to me. In OpenSCAD it's parametric by necessity. I said this in another comment, but the other programs I've worked with in GUI are most certainly not high end pieces of software: tinkercad, freecad, sketchup.
I'm not doing complex character model designs, I'm usually building functional prints like enclosures or cases. It certainly sounds like there are features of better CAD software that makes parametric the default?
FreeCAD is definitely parametric but I hear you that the interface doesn't make it obvious. It might be worth another look particularly since it's interoperable with OpenSCAD and can work on CSG trees within the interface
At least you've inspired me to try it and see if it's "worth writing home about"
I think I understand this — I mean, OpenSCAD was my brief gateway to parametric CAD, and then I got to FreeCAD via brief stepping stones of CadQuery and other packages.
OpenSCAD isn't really parametric CAD. It's a programming language; it's parametric for that reason. But it's not really even CAD, at another level; it does nothing to "aid" your design work, it has no real interim abstraction of its own product.
FreeCAD, though, is profoundly parametric, through and through, and really always has been. Indeed the parametric aspects are the main thing that made it workable before the TNP mitigations were added. It is not a limited CAD package, by any means. It's just a somewhat unfriendly one with a CAD kernel that has some limitations. Really it's almost better understood as a 3D IDE with some workflow affordances.
If you are stuck trying to get your head into how FreeCAD works, there are now three really good ways on Youtube: the Mango Jelly Solutions videos are incredible, the Shawn Hymnel/Digikey FreeCAD and 3D Printing course is good, and there are great recent videos by Deltahedra.
But what you will be able to make with it, once you get your head into it, is night and day different to what is possible with OpenSCAD. Because your parametric work in FreeCAD (or other CAD packages) can operate on the geometry of the result of previous operations.
Give it a try in the New Year with FreeCAD 1.1 when it is released.
If you want another stepping stone from OpenSCAD to FreeCAD or any other package, I really recommend you look at CadQuery/Build123D. This will give you a similar coding approach but it will introduce you to operations on the true faces, edges and vertexes of the output of other operations.
(FWIW I would not say that Sketchup is not high end, either. It's not to my tastes but it is quite powerful)
A properly parameterized model shouldn't have the issue with having to nudge everything manually after a trivial change.
I had the change the height of an entire enclosure to accommodate a taller than anticipated PCB, and simply edited the sketch at the top of my design tree that defined the overall dimensions.
It took about 5 minutes to adjust the odd broken fillet and change some mates in assembly and it was done. No fidgety mouse movements. I actually do a lot of mech design on a laptop with a trackpad, arrow keys for view changes and numeric dimensioning for 95% of everything else.
> Every time I've used as a CAD GUI program I would get to this point where I would need to alter a single dimension by 0.25mm and realize that _all_ of my fastener holes, cutouts, etc have to be nudged with the keyboard or mouse to accommodate it.
I am just starting to learn CAD and FreeCAD - also dabbled a bit in OpenSCAD. But I do know that FreeCAD has Spreadsheets [1] and Configuration Tables [2] which allows you to define your model parameterically and changes values as needed.
Spreadsheets are really slow in FreeCAD. I'd suggest you look into Varsets [0] if you don't need some of the fancier capabilities that spreadsheets provide.
Yes, VarSets are definitely better (more granular dependency recalculations).
The little-known Configuration Tables aspect of Spreadsheets is absolutely worth using, though, and has no analog in the VarSets scheme at this point. Once you get that set up it is great fun.
It’s a fantastic feature and works really well, my problem is I can never invest the required time to learn the interface. It all falls apart when I need to switch modes to move something or whatever. With scad can usually knock whatever I want together pretty quickly without having to relearn how to use the tool.
> I would really recommend using the git master than the latest release though.
This. The master version is so much further ahead of the last tagged version. The render time can be orders of magnitude faster for more complex models.
Agree but you quickly run into its limitations. Like if you 3d print something, you need to eliminate when possible sharp edges. That's not fun to do with OpenSCAD.
The great thing about OpenSCAD is that it makes it easy to 3D model things which may be described using spheres, cylinders, and cubes which are stretch, and/or rotated, and arranged in 3D space.
The awful thing about OpenSCAD is that what one can model in 3D is limited by one's ability to mathematically stretch, rotate, and/or arrange spheres, cylinders, and cubes in 3D.
For folks who want "real" (read mutable in normal terms of scope) variables there is a Python-enabled fork (which should become part of the main release presently:
Not just that but it also positions everything in absolute coordinates and does not have the ability to reason about solids, just surfaces. Basically if you want to model something like a bolt you need to create a cylinder for the shaft, a separate head of the bolt, and then a thread profile you can rotate around the cylinder. You must ensure there is enough overlap between these three separate parts so the resultant object is a single surface and not three separate ones.
You can use modules to create a semblance of relative measurements but you still cannot do things like “attach this surface of object A to that surface of object B)”. In practice this means that if you want to create something like a spacer or a bracket you can do that easily enough. But if you want to make a part that matches some real world design you are stuck doing a lot of caliper measurements and math to try to create a part that lines up correctly. The you 3D print it and find that you positioned some hole based on its edge and not center and so nothing quite fits.
OpenSCAD is easy to start but difficult to scale because of these limitations and because once you hard-code any measurement you are stuck with it. The “proper” way to do this is to give everything a variable but honestly that makes reasoning about how to line things up even more difficult. “Does base_width include the width of the vertical walls? What about the margin to make the parts fit together?”
I have never been able to understand how things like FreeCAD lay out their UI. TinkerCAD is relatively simple but clearly a lot less powerful. I did try cadquery which solved a lot of OpenSCAD’s issues by having all offsets be relative by default but also introduces a few issues of its own.
One tip I will give about OS: grab a copy of the latest beta/dev release. The renderer is several orders of magnitude faster.
It would be nice to have more declarative constraints. The solvespace file format is plain text and it almost feels like you could write it by hand, but that would be a lot of manual record keeping. and you would loose all that imperative goodness. Perhaps you could have an imperative layer(say python or lisp or forth) that outputs the declarative layer(solvespace) and then solvespace renders(picture or stl) the declarative layer.
I think a text input option for Solvespace which was optimize for readability and usability would be _very_ interesting approach, esp. if Solvespace was able to write back out to the same format, and it allowed math/variables/parameters and supported the same in the UI.
> The great thing about OpenSCAD is that it makes it easy to 3D model things which may be described using spheres, cylinders, and cubes which are stretch, and/or rotated, and arranged in 3D space.
It also has hulls and minkowski sums, which are powerful once you understand them.
Aren't hulls just a direct connection of the edges of two shapes (which could be simulated by a series of duplications) while Minkowski is "just" a matter of putting spheres along the edges of an object to round the straight edges?
So, spheres and cylinders and cubes placed, rotated, stretched and placed mathematically.
You can also make more complex shapes if you're willing to define points, even on a 2D plane that you can then extrude. Downside is that it's basically a MENSA test to define all of the points in the correct order. I've done it a few times, but it's never fun.
It has many language bindings, including python and js. Though the js backend is not parallel because it uses wasm, and we had problem with mimalloc memory usage with pthread enabled.
From my testing, the CSG operations, with post-processing, don’t produce watertight meshes. And being focused on printing, it doesn’t support different colors for the CSG operands. My use case is animation/games, so I’m reimplementing the CSG with a watertight b-rep.
Don't people think this is one tool that would greatly benefit from using the very fastest languages available? Where's the C++, Rust, maybe even FORTRAN version?
This is only the language for describing the volumes. That's not heavy, rather the importance is that you can express the ideas you want. The heavy lifting of rendering and computing how volumes interact etc is already implemented in native code.
Another interesting option is FreeCAD, which is scriptable in Python but its primary interface is a GUI. So you can use a script to create things programmatically, edit graphically, or both.
FreeCAD sounds great but in practice it’s sooo slow.
If you are coming from SolidWorks, Fusion360, Inventor, or OnShape, it won’t take long before you start finding that there are a lot of things missing from it.
I'm coming from Fusion, advanced hobbyist, I can't find anything missing. </anecdata>
There is a problem though - sometimes what you want requires deep understanding. It's less user friendly, polished, and documented. That's also relevant to the performance - it's easy to cause performance issues. But I remember the same was also applicable to Fusion.
Of course FreeCAD is less user friendly, polished, and documented. It's open source. Open source people do not get GUIs. They think command line.
It's taken decades for artists and graphic designers to nag the GIMP and Blender people into usable interfaces, and they're still inferior to Photoshop and Maya.
I ended up adding the https://github.com/BelfrySCAD/BOSL2 library to OpenSCAD and it had some reasonable options for some gear and rack-and-pinion modeling that I needed to do.
(3D printing a sacrificial gear for a seat position adjustment mechanism)
I’ve used OpenSCAD for 3D printing random objects for years. It’s the perfect tool for designing super simple geometric objects, because it giant demands that you remember hardly anything about his the interface works. Contrast with Fusion 360 or any other more powerful tool, which are fantastic if you use them daily but a slog of you only boot them up a few times a year.
Also with OpenSCAD, you can feed the documentation to your favorite LLM and ask it for a starter design of whatever you are building. (Or you can skip the documentation; it is in the trading data after all.) Maybe in the future that SVG Pelican on a bike test will be a 3D model in OpenSCAD.
For me as a casual 3d-modeler, my favorite thing about OpenSCAD is that I don't have to learn a new application the size of Photoshop with everything hidden 7 levels deep in some menu that is probably intuitive for some people who learned CAD in the 80s.
Instead it's basically like graphics programming, with a couple of basic primitives, some linear transformations and a bit of set theory. When I do a model a month and get back to previous work, I read a few lines of code and know exactly how I achieved the result.
I was once a big OpenSCAD user myself but I'm really skeptical that there are many use cases where it's actually more intuitive than a traditional CAD program, even if you're a programmer. It's true CAD programs have a huge amount of features but the basic sketch, extrude, revolve, and loft tools aren't conceptually difficult and are basically the same between Onshape, Fusion, Solidworks, etc. Those tools are sufficient to make 99.99% of OpenSCAD models I'm seeing.
I also have the opposite experience about understanding previous scripts. Unless it's dead simple I'm usually thinking why the hell did I multiply this thingy by sqrt(3)/2 plus this other thing. Maybe a documentation problem, but it's inescapable that sometimes you need a lot of math for what are trivial constraints in an interactive sketch. A real CAD program will let you roll back to any feature to figure out how it's constructed step by step so there's really nothing to decipher.
I've been trying to model joints for woodworking, and in traditional tools, the shapes I wish to arrive at verge on nightmarish, while I was able to knock them out in OpenSCAD in pretty short order --- except that when I sent a 1" x 2" x 1" test joint to a CAM program, it took some 18 minutes and generated a ~140MB G-code file, hence my working on:
Yeah I agree. OpenSCAD is good for highly parametric modelling: fasteners, gears, generative art, ... that's about it. Most things aren't like that, and a traditional parametric CAD program is 10x easier.
Oh I had no idea that OpenSCAD was a programmatic toolkit. I recently bought a 3D printer and I don't model so much as describe to Claude Code how to write a Python script that will generate the required STL that I then rescale or whatever in Bambu Studio. LLMs are great at code-oriented stuff so I've stayed away from traditional modeling tools because I assumed you'd have to point and click and so on and I don't really want to learn the ins and outs of their interface. I just need the right mesh made.
The chatbots kept recommending I try using OpenSCAD but I resisted without even giving it a look. The results I had with just the Python script are quite adequate for the tasks I had. You can just ask the LLM to add a fillet to a vertical pin on a plane or to chamfer some edge and it is pretty good at doing it.
I'm going to try using OpenSCAD for things in the future. Does anyone else use exclusively an LLM with OpenSCAD (I used Claude Code and Codex) and if you do what did you do to make it more effective? The Python script wouldn't always generate printable meshes so I had to give it a check script to operate on.
- functional programming model --- some folks find not having traditionally mutable variables limiting
- output is as an STL, or DXF using polylines
- native objects are spheres, cylinders, cubes, with functions for hull and Minkowski, so filleting and other traditional CAD operations can be difficult
Once had a complex model that would fully crash and lockup fusion, but once redone in openscad rendered after a little while. (badly designed + slow pc at tye time)
It is amazing. I spend more time in OpenSCAD than in any other program I use and I'm amazingly productive with it. 3 to 4 cycles / day, the longest time is waiting for the printer to cough up the next iteration, then it is building debugging and improving again.
The power of parametric cad is such that I wouldn't be a 10th as productive using an interactive cad system. And because it is effectively software you are writing (even if it compiles into physical objects) you can use all of the goodies that you can use to manage software. Diff files, git, kompare, branching, merging. It is nothing short of amazing, it is like I have a design team and a prototype injection molding facility in one. And the turnaround time is something you'd have killed for in the 90's.
'Normal' cad software is parametric in an entirely different sense. You don't normally build up from entities just like you would in software, which you can then manipulate symbolically.
There are cad packages that can do this but unlike OpenSCAD the main interaction there is the 3D window, not the text editor.
Though AutoCAD of course had this with AutoLISP since 1986.
Interestingly, I'm not sure which has the steeper learning curve, OpenSCAD or AutoLISP. OpenSCAD is really great once it clicks but most people give up long before then.
I went from OpenSCAD -> cadquery/build123d -> Zoo/KCL
It still is early days, and it needs some more helper functions but it's really nice having two-way capabilities (not just code -> model, but also the reverse).
Of course having Text-to-model as a first class citizen is also nice.
I want to like Zoo but the rendering engine is so buggy currently that it’s not really usable for more than simple shapes. The text-to-CAD feature they highlight is slow and error-prone, so much so that they explicitly use a “prebuilt” version in the tutorial, and each time I tried it, it gave tool errors or took so long I just did it manually.
I have played with this but been underwhelmed. However I do think probably on the right track.
I know the ecosystem not-at-all (sum total knowledge of the CAD ecosystem is that my kids got a Bambu printer for Hanukkah) but it feels to me that current LLMs should be able to generate specs for something like https://partcad.readthedocs.io/en/latest/, which can then be sliced etc.
Curious to know what others think? I come at this from the position of zero interest in developing the fine design skills needed to master but wanting to be able to build and tweak basic functional designs.
It's super useful, been using with my 3D printer to print things such as an adapter to connect a Canon EF lens to night vision tube and parts to link motorised linear stages together.
If you are a programmer OpenSCAD is likely for you. It certainly has benefits in things that are repeating patterns (gears and such)...and if your mind is good at visualizing things in "code" things will likely go a lot faster.
I personally do better with CAD software such as fusion or freecad since my mind doesn't work in the code realm since I have more of a hardware mindset. Translating the picture in my head to code is more difficult than drawing it using the standard CAD set of tools.
My opinion on OpenSCAD is that it is a very useful piece of software which many have used to make some very interesting things. If you have a background in code I recommend giving it a go. I largely view it as "the coder's CAD".
I was just about to say the same: OpenSCAD is CAD for programmers. It's very different from what's generally considered "CAD".
That's not necessarily a bad thing; there's a clientele for it, especially here on HN. But as a mechanical engineer who's used quite a few industry standard CAD systems, I'm sorry to say I wouldn't touch it with a ten foot pole.
Funnily, just a few days ago I tried FreeCAD, and found it to be better than I had expected.
It’s still strictly worse than what these models are capable of for general-purpose coding, but for simple tasks where precision isn't the bottleneck, it's surprisingly decent.The "aha" moment for me was an image-to-object workflow: found a geometric design on the web --> generated OpenSCAD to match the image --> 3D printed it. Going from seeing a JPEG to holding the physical object in a few hours.
I rage-quited every other CAD program. Then I found OpenSCAD. Now I'm looking forward to work in it every time I need to do some 3d modeling (usually new part model for kicad or some other project).
I find myself using OpenSCAD regularly to 3D print little things for the house. (Most recently: hooks to attach Christmas lights to our roof deck's glass walls)
And when something gets too trick, ChatGPT is amazing at writing in it. Often it nails the whole design in the first try, like https://bsky.app/profile/bradfitz.com/post/3maelwomyw22n to mask off certain Raspberry Pi pins to make reassembly of projects easier later.
OpenSCAD has become my go to with my 3-D printer for dumb little things. And the best part is LLMs are getting decent / pretty good with it!
My favorite thing I’ve printed is a little downsize coupler for the cool shirt system I built for my spec miata. It’s realllly silly & small thing, but it saved me!
Mind you, it can't export to step file. That makes it impossible to re-use the models in other CADs to make assimblies. Also it's tedious to use for 3d printing when you want to include modifier objects with your model. Otherwise it's great and good enough for part modeling
This is important and should be a given. But the more interesting challenge is to highlight the object you’re editing (where your cursor is). It’s not clear even how to exactly visualize it (it could be inside subtract of union of subtract etc).
I came here to ask how good LLMs are at working with this. I wonder if a person could take it a step further with some MCP tools that the agent could use to verify and work with the design.
openscad is quite nifty for small geometric projects. unfortunately it lacks some Features that make most bigger cad programs really useful... for example: - the ability to select faces/paths from a render, which can be hugely helpful when modifying complex models. - the ability to do constrained sketching in both 2d and 3d - caching at intermediate render levels - nested Projects and joining parts with mechanical constraints. it's still pretty nifty but very niche. I personally would dream of having the tools of a tool like fusion 360 or Catia, but in a gilly textual progemmatic way, while keeping the ability to select objects from the rendrr view.
I don't really see why that code is better, more logical, more readable or more robust than the equivalent quite trivial parametrics in more or less any GUI CAD program, and I think the geek discourse is really harmed by people who don't understand the value of the things that OpenSCAD can't ever offer.
OpenSCAD is great! I used it to create a bunch of things to cut on a CNC router over the years. Best achievements were a scale model of Mount Rainier and some one-piece picture frames with text cut into them.
Yes. The "official release" is just so old as to be useless at this point. They should either update it or take it down and point people at github or something, IMO.
I use the latest version all the time. The newer renderer ("manifold", IIRC) is much faster, and there are newer facilities that make it possible to build 3MF files containing multiple objects for multi-color printing, though that takes a bit of thought to do correctly.
Yes everything this person said is correct. The Manifold backend is no joke, probably 100x faster.
To do multi-color printing it’s pretty easy now, just turn on the poorly named feature in preferences called “lazy-unions”. This will make it so that each top level object in your file gets exported as a separate subobject in the 3mf file.
Yes, but the main downloads on the site are very old for some reason. Just get the nightly version instead, and then in Preferences -> Advanced -> Backend change it to “Manifold”. It will make your models “render” 10x faster (or more!).
I'm a programmer. I once had an idea stuck in my head for a 3d model that I just needed to get down somewhere. I tried learning the basics of AutoCAD but after 2 days of tutorials I still felt overwhelmed.
I looked into alternatives and learned about OpenSCAD. The immediate visual feedback makes picking up the language a breeze. Within an hour of downloading I familiarized myself with the language and had manifested my idea into a 3d model
I think that's a perfect example of a use-case where OpenSCAD shines. It's extremely easy to pick up if you have programming experience and it might even be a good thing to learn before moving onto more professional CAD software. From a teaching perspective, being able to have almost immediately-useful output is priceless
The thing is, I've crashed-and-burned every time I've tried to do traditional 3D CAD --- the closest I've come to success was making it all the way through the tutorial for Dune 3D:
OpenSCAD "just works", even on quite limited hardware, and if one has trouble modeling something, well, arriving at a solution is just a matter of learning the appropriate mathematics.
I love the model, it's nice to be able to generate things parametrically instead of grabbing knots with the mouse. so I use scad pretty often.
but it has real problems -
the language is weird and unfortunate. not anything super fatal, just the obvious product of evolution that would be more cohesive if it were architected wholesale
epsilons are really unfortunate. you have to expect that after getting what you want in the whole, you're going to have to scan over the whole thing and look for cracks or collision where there shouldn't be
performance is quite sad. here you are happy going back and forth between the view and text windows, but as you go on, it starts taking .. minutes.. to update the view once you have a reasonably complicated geometry
high-level operators would also be nice. I made the mistake of using a thread library once, not only did that make my model unrenderable, there was so much noise in the model and the manufacturing process I had to make 3 expensive test prints in sintered nylon to get the fit right. (I'm thinking an annotation on a cylinder that says 'standard 1mm thread')
It actually renders things incredibly fast if you get the nightly version and set the backend to Manifold. It is probably 100x faster (!!). In fact it renders so fast that I put a render() command at the top of my hierarchy so that everything just renders all the time, it’s faster and more performant. I make incredibly complex models with it too, with hundreds of holes, complex svg files with text in them, etc.
https://github.com/fogleman/sdf
One big plus to doing it this way is that it's "just" Python and you can use arbitrary logic to help construct your model.
You can even load an existing 3D mesh and operate on it as an SDF. Great for hollowing, chopping, eroding/dilating, etc. existing models.
I should probably do more with this project. I think there's a lot of interest in this space.
I recently also got annoyed with OpenSCAD and its limitations and therefore started experimenting with Build123d. I'm very much a beginner in the CAD space and would love to understand what inspired you to build sdf.
My basic understanding is that STL files are essentially like Bitmap images and store a list of triangles and their positions, whereas STEP files are more like Vector art where there is a list of instructions on how to build the model. Most CAD GUI programs also operate on a similar model to vector art where they record a list of operations one on top of another. It's why STEP files are a standardized format and can be imported / exported from most GUI based CAD builders. I think.
Given that SDF also seems like it builds only STL files (I could be wrong), wouldn't learning build123d or CadQuery work better if one cares about compatibility with existing GUI based CAD modeling software?
Additionally, atleast build123d offers a similar conceptual model to using Fusion360 and FreeCad - I have limited experience here - but essentially you sketch something in 2D on a particular plane, and then apply some operations to convert it to 3d in a particular manner - the simplest being extruding. This means the mental modeling of how to construct something is very similar across both GUI based CAD programs and Build123d, and that makes it easier for me to jump between GUI based and code based CAD modelling.
I'd love to understand your point of view, and learn more.
[0] - https://github.com/gumyr/build123d
[1] - https://github.com/CadQuery/cadquery
This has my instant interest. Multiple times I have wanted to take an existing .STL file and cut a hole on it or add another object to it and have never had success.
I've tried things like Meshlab, but while the interface has what appears to be a hundred different functions, attempting to use anything returns some error code that requires a PhD to understand and none of the "repair" functions seem to help.
I mean seriously: Mesh inputs must induce a piecewise constant winding number field.
How the hell am I supposed to accomplish that on a STL file?
https://github.com/fogleman/sdf/blob/main/examples/mesh.py
You basically just say:
f = Mesh.from_file(path).sdf(voxel_size=0.25, half_width=1)
Then you can operate on `f`.
Removing faces from an STL and adding other objects is quite straightforward. Previously, Autodesk had Meshmixer and 123D, I guess Meshmixer is still available: https://meshmixer.org/ and I found it to be great for quick editing of the type you're describing.
I would really recommend using the git master than the latest release though. The last release was 2021 but they are still actively working on it and it's much faster now.
I also have to recommend the BOSL2 library which means you don't have to implement all of those one million features from typical CAD software yourself. Its definitely got a bit of a learning curve but the fact that you can always default back to vanilla OpenSCAD and that you can actually see how stuff is implemented makes it much more satisfying to me to learn than learning what all the traditional CAD GUI buttons do.
I love OpenSCAD. I've been 3D printing for a while, but I never really got to a place where I could design interesting parts until I started to get the precision of doing models in code. Sometimes it is slower, for sure.
Every time I've used as a CAD GUI program I would get to this point where I would need to alter a single dimension by 0.25mm and realize that _all_ of my fastener holes, cutouts, etc have to be nudged with the keyboard or mouse to accommodate it. The input devices lack precision for that kind of task, and having to repeat the operation dozens of times (or bulk select) gave me a terrible sinking feeling, and I'd often just step away and give up on the design at that point out of frustration. I try to approach everything in OpensSCAD in a way that means I never have to experience that feeling again.
I will also say that doing everything from scratch in OpenSCAD would be it's own special kind of hell. Libraries like [BOSL2](https://github.com/BelfrySCAD/BOSL2) provide a good set of core ideas and preferences that help set you on a good path. A good example: BOSL2 shapes tend to have a "center origin" by default, which is different than the OpenSCAD default, but makes doing transforms later way easier.
Anyway, happy to see OpenSCAD getting some attention here :)
There seems to be some fundamental misunderstanding of CAD here. I can't imagine how you could even design something in CAD in a way that you would end up in this situation.
When I'm doing something more sophisticated I use SolveSpace, but I'm a lot slower with that.
What.
This makes no sense. This isn't PowerPoint; your holes and cutouts are supposed to be parameterized. How are they even supposed to be at the proper position in the first place?
As a CAD user, this is like e.g. a coder seeing someone write code with global variables everywhere.
I'm not doing complex character model designs, I'm usually building functional prints like enclosures or cases. It certainly sounds like there are features of better CAD software that makes parametric the default?
At least you've inspired me to try it and see if it's "worth writing home about"
https://wiki.freecad.org/OpenSCAD_Workbench
OpenSCAD isn't really parametric CAD. It's a programming language; it's parametric for that reason. But it's not really even CAD, at another level; it does nothing to "aid" your design work, it has no real interim abstraction of its own product.
FreeCAD, though, is profoundly parametric, through and through, and really always has been. Indeed the parametric aspects are the main thing that made it workable before the TNP mitigations were added. It is not a limited CAD package, by any means. It's just a somewhat unfriendly one with a CAD kernel that has some limitations. Really it's almost better understood as a 3D IDE with some workflow affordances.
If you are stuck trying to get your head into how FreeCAD works, there are now three really good ways on Youtube: the Mango Jelly Solutions videos are incredible, the Shawn Hymnel/Digikey FreeCAD and 3D Printing course is good, and there are great recent videos by Deltahedra.
But what you will be able to make with it, once you get your head into it, is night and day different to what is possible with OpenSCAD. Because your parametric work in FreeCAD (or other CAD packages) can operate on the geometry of the result of previous operations.
Give it a try in the New Year with FreeCAD 1.1 when it is released.
If you want another stepping stone from OpenSCAD to FreeCAD or any other package, I really recommend you look at CadQuery/Build123D. This will give you a similar coding approach but it will introduce you to operations on the true faces, edges and vertexes of the output of other operations.
(FWIW I would not say that Sketchup is not high end, either. It's not to my tastes but it is quite powerful)
I had the change the height of an entire enclosure to accommodate a taller than anticipated PCB, and simply edited the sketch at the top of my design tree that defined the overall dimensions.
It took about 5 minutes to adjust the odd broken fillet and change some mates in assembly and it was done. No fidgety mouse movements. I actually do a lot of mech design on a laptop with a trackpad, arrow keys for view changes and numeric dimensioning for 95% of everything else.
I am just starting to learn CAD and FreeCAD - also dabbled a bit in OpenSCAD. But I do know that FreeCAD has Spreadsheets [1] and Configuration Tables [2] which allows you to define your model parameterically and changes values as needed.
How good this is, I don't know yet.
[1] https://wiki.freecad.org/Spreadsheet_Workbench [2] https://wiki.freecad.org/Configuration_Tables
[0] https://wiki.freecad.org/Std_VarSet/en
The little-known Configuration Tables aspect of Spreadsheets is absolutely worth using, though, and has no analog in the VarSets scheme at this point. Once you get that set up it is great fun.
This. The master version is so much further ahead of the last tagged version. The render time can be orders of magnitude faster for more complex models.
or with Homebrew you can do `brew install --cask openscad@snapshot` to install the latest snapshot version.
Or, browse all the snapshot builds here: https://files.openscad.org/snapshots/
(as of this comment, the last snapshot build is from yesterday)
https://github.com/BelfrySCAD/BOSL2/wiki/rounding.scad
https://github.com/BelfrySCAD/BOSL2/wiki/Tutorial-Rounding_t...
It is a useful tool for programmatically describing either very simple or heavily geometric objects. For everything else it's the wrong tool.
The awful thing about OpenSCAD is that what one can model in 3D is limited by one's ability to mathematically stretch, rotate, and/or arrange spheres, cylinders, and cubes in 3D.
For folks who want "real" (read mutable in normal terms of scope) variables there is a Python-enabled fork (which should become part of the main release presently:
https://pythonscad.org/
You can use modules to create a semblance of relative measurements but you still cannot do things like “attach this surface of object A to that surface of object B)”. In practice this means that if you want to create something like a spacer or a bracket you can do that easily enough. But if you want to make a part that matches some real world design you are stuck doing a lot of caliper measurements and math to try to create a part that lines up correctly. The you 3D print it and find that you positioned some hole based on its edge and not center and so nothing quite fits.
OpenSCAD is easy to start but difficult to scale because of these limitations and because once you hard-code any measurement you are stuck with it. The “proper” way to do this is to give everything a variable but honestly that makes reasoning about how to line things up even more difficult. “Does base_width include the width of the vertical walls? What about the margin to make the parts fit together?”
I have never been able to understand how things like FreeCAD lay out their UI. TinkerCAD is relatively simple but clearly a lot less powerful. I did try cadquery which solved a lot of OpenSCAD’s issues by having all offsets be relative by default but also introduces a few issues of its own.
One tip I will give about OS: grab a copy of the latest beta/dev release. The renderer is several orders of magnitude faster.
Sure you can, but openscad is an imperative language so you need to do it in an imperative manner.
It would be nice to have more declarative constraints. The solvespace file format is plain text and it almost feels like you could write it by hand, but that would be a lot of manual record keeping. and you would loose all that imperative goodness. Perhaps you could have an imperative layer(say python or lisp or forth) that outputs the declarative layer(solvespace) and then solvespace renders(picture or stl) the declarative layer.https://github.com/BelfrySCAD/BOSL2/wiki/screws.scad
Manifold backend also eliminates the need to avoid coincident faces.
It also has hulls and minkowski sums, which are powerful once you understand them.
So, spheres and cylinders and cubes placed, rotated, stretched and placed mathematically.
Which avoids using the OpenSCAD language, but also means you can't use BOSL2. Might as well use FreeCAD.
https://openjscad.xyz/
https://github.com/jscad/OpenJSCAD.org
https://replicad.xyz/
If you wish to use Rust for 3D modeling directly there is:
https://fornjot.app/
(the developer of which is actually working on a BREP kernel)
If you are coming from SolidWorks, Fusion360, Inventor, or OnShape, it won’t take long before you start finding that there are a lot of things missing from it.
There is a problem though - sometimes what you want requires deep understanding. It's less user friendly, polished, and documented. That's also relevant to the performance - it's easy to cause performance issues. But I remember the same was also applicable to Fusion.
(3D printing a sacrificial gear for a seat position adjustment mechanism)
Also with OpenSCAD, you can feed the documentation to your favorite LLM and ask it for a starter design of whatever you are building. (Or you can skip the documentation; it is in the trading data after all.) Maybe in the future that SVG Pelican on a bike test will be a 3D model in OpenSCAD.
Instead it's basically like graphics programming, with a couple of basic primitives, some linear transformations and a bit of set theory. When I do a model a month and get back to previous work, I read a few lines of code and know exactly how I achieved the result.
I also have the opposite experience about understanding previous scripts. Unless it's dead simple I'm usually thinking why the hell did I multiply this thingy by sqrt(3)/2 plus this other thing. Maybe a documentation problem, but it's inescapable that sometimes you need a lot of math for what are trivial constraints in an interactive sketch. A real CAD program will let you roll back to any feature to figure out how it's constructed step by step so there's really nothing to decipher.
https://github.com/WillAdams/gcodepreview
The chatbots kept recommending I try using OpenSCAD but I resisted without even giving it a look. The results I had with just the Python script are quite adequate for the tasks I had. You can just ask the LLM to add a fillet to a vertical pin on a plane or to chamfer some edge and it is pretty good at doing it.
https://wiki.roshangeorge.dev/w/Blog/2025-12-01/Grounding_Yo... if you want to roughly see the workflow.
I'm going to try using OpenSCAD for things in the future. Does anyone else use exclusively an LLM with OpenSCAD (I used Claude Code and Codex) and if you do what did you do to make it more effective? The Python script wouldn't always generate printable meshes so I had to give it a check script to operate on.
Years later, I never actually got the hang of CadQuery, and I'm wondering if it was a mistake to write off OpenSCAD.
I am pretty new to CAD, so I don't actually know when I would run into OpenSCAD's limitations.
- functional programming model --- some folks find not having traditionally mutable variables limiting
- output is as an STL, or DXF using polylines
- native objects are spheres, cylinders, cubes, with functions for hull and Minkowski, so filleting and other traditional CAD operations can be difficult
The power of parametric cad is such that I wouldn't be a 10th as productive using an interactive cad system. And because it is effectively software you are writing (even if it compiles into physical objects) you can use all of the goodies that you can use to manage software. Diff files, git, kompare, branching, merging. It is nothing short of amazing, it is like I have a design team and a prototype injection molding facility in one. And the turnaround time is something you'd have killed for in the 90's.
This sounds like parametric and interactive CAD are polar opposites. Normal CAD software is generally parametric too.
The other points about the advantage of text files still applies though.
There are cad packages that can do this but unlike OpenSCAD the main interaction there is the 3D window, not the text editor.
Though AutoCAD of course had this with AutoLISP since 1986.
Interestingly, I'm not sure which has the steeper learning curve, OpenSCAD or AutoLISP. OpenSCAD is really great once it clicks but most people give up long before then.
Mathematica however is Lispy enough and has a lot of helpful geometry primatives and can export STL
I went from OpenSCAD -> cadquery/build123d -> Zoo/KCL
It still is early days, and it needs some more helper functions but it's really nice having two-way capabilities (not just code -> model, but also the reverse).
Of course having Text-to-model as a first class citizen is also nice.
I know the ecosystem not-at-all (sum total knowledge of the CAD ecosystem is that my kids got a Bambu printer for Hanukkah) but it feels to me that current LLMs should be able to generate specs for something like https://partcad.readthedocs.io/en/latest/, which can then be sliced etc.
Curious to know what others think? I come at this from the position of zero interest in developing the fine design skills needed to master but wanting to be able to build and tweak basic functional designs.
Currently I'm playing with a gear library which is part of BOSL2 (https://github.com/BelfrySCAD/BOSL2/wiki/gears.scad), to make something to rotate a polariser in my microscope.
I personally do better with CAD software such as fusion or freecad since my mind doesn't work in the code realm since I have more of a hardware mindset. Translating the picture in my head to code is more difficult than drawing it using the standard CAD set of tools.
My opinion on OpenSCAD is that it is a very useful piece of software which many have used to make some very interesting things. If you have a background in code I recommend giving it a go. I largely view it as "the coder's CAD".
That's not necessarily a bad thing; there's a clientele for it, especially here on HN. But as a mechanical engineer who's used quite a few industry standard CAD systems, I'm sorry to say I wouldn't touch it with a ten foot pole.
Funnily, just a few days ago I tried FreeCAD, and found it to be better than I had expected.
https://github.com/rahulgarg123/openscad-mcp
It’s still strictly worse than what these models are capable of for general-purpose coding, but for simple tasks where precision isn't the bottleneck, it's surprisingly decent.The "aha" moment for me was an image-to-object workflow: found a geometric design on the web --> generated OpenSCAD to match the image --> 3D printed it. Going from seeing a JPEG to holding the physical object in a few hours.
And when something gets too trick, ChatGPT is amazing at writing in it. Often it nails the whole design in the first try, like https://bsky.app/profile/bradfitz.com/post/3maelwomyw22n to mask off certain Raspberry Pi pins to make reassembly of projects easier later.
https://github.com/gumyr/build123d
My favorite thing I’ve printed is a little downsize coupler for the cool shirt system I built for my spec miata. It’s realllly silly & small thing, but it saved me!
It's neat that I can tell the computer what I want in words and then have that object come out of the 3D printer
I have not yet invented any other improvement.
I tried decimal points, but that was stupid, you just add "/100" if you want micrometer accuracy.
And even if it’s not perfect it saves a lot of time looking up the documentation and generally gets the relationships between objects right.
https://makerworld.com/en/models/2040939-accessible-christma...
Ok if you want to generate a couple of cubes, but if you want anything advanced the kernel quickly falls apart
Which you can also use directly instead by writing C++. Trivial operations are two orders of magnitude faster and complex ones every faster.
Assuming you make all the necessary adjustements in preferences.
https://github.com/WillAdams/gcodepreview
I don't really see why that code is better, more logical, more readable or more robust than the equivalent quite trivial parametrics in more or less any GUI CAD program, and I think the geek discourse is really harmed by people who don't understand the value of the things that OpenSCAD can't ever offer.
I use the latest version all the time. The newer renderer ("manifold", IIRC) is much faster, and there are newer facilities that make it possible to build 3MF files containing multiple objects for multi-color printing, though that takes a bit of thought to do correctly.
To do multi-color printing it’s pretty easy now, just turn on the poorly named feature in preferences called “lazy-unions”. This will make it so that each top level object in your file gets exported as a separate subobject in the 3mf file.
That said, there are often times software gets so stable that not having a new release for years is fine. Maybe this is one of them?
(I'm very new to OpenSCAD so I haven't run into bugs yet... But maybe it's pretty solid?)
https://openscad.org/downloads.html#snapshots
The big distinction is that those work implicitly, while OpenSCAD requires you to be implicit.
I looked into alternatives and learned about OpenSCAD. The immediate visual feedback makes picking up the language a breeze. Within an hour of downloading I familiarized myself with the language and had manifested my idea into a 3d model
I think that's a perfect example of a use-case where OpenSCAD shines. It's extremely easy to pick up if you have programming experience and it might even be a good thing to learn before moving onto more professional CAD software. From a teaching perspective, being able to have almost immediately-useful output is priceless
https://www.blockscad3d.com/editor/
I just wish that they'd add the balance of the language/fix some bugs.
https://news.ycombinator.com/item?id=37979758
https://news.ycombinator.com/item?id=40228068
OpenSCAD "just works", even on quite limited hardware, and if one has trouble modeling something, well, arriving at a solution is just a matter of learning the appropriate mathematics.
but it has real problems - the language is weird and unfortunate. not anything super fatal, just the obvious product of evolution that would be more cohesive if it were architected wholesale
https://pythonscad.org/