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Comment by richk449 | Hacker News Reader

I’ve been using cadquery and build123 with Claude code and I find it incredibly painful.

What is your workflow for llm integration to openscad?

I just ask it for what I’m looking for (doing very simple “spare part” level at home 3d printing, nothing fancy or elaborate) and it gives me a starting point. Then I sometimes just edit the scad code by hand, and some times I ask the AI to revise, sometimes a mix (many iterations).

For very simple geometries it works great, but it very quickly becomes apparent that there’s a bit of a disconnect between “LLM views image” and “LLM emits scad that looks like that image” when it comes to anything non-trivial.

Still gives me a starting point I can mess with, which is great since I have zero CAD training or experience.

(I’m not the commenter you replied to)

Tbh that sounds harder than just learning CAD, which is really not that difficult if you use a proper parametric editor - I would recommend SOLIDWORKS first. It's got the easiest UX so is ideal for learning. They actually have a vaguely reasonably priced subscription now, but IMO it's still way too much for occasional hobby use so I'd recommend just pirating it (which is easy).

Once you have learnt a bit then the only FOSS options that are worth a damn are a) SolveSpace which is quite good and light, has a slightly quirky UI (but not in a bad way) but unfortunately has some critical missing features at the moment - notably bevels/chamfers. Although I did see someone made a sloppy PR to add them so we'll see where that goes.

Or b) FreeCAD which is actually good now and fairly close to SOLIDWORKS (at least for the basic stuff you're likely to use) and has a reasonably good UX. Some rough edges still but overall it's very usable. Good enough that I reach for it instead of pirating SOLIDWORKS these days.

The basic workflow is pretty simple:

1. Make some planes, referenced from existing geometry. 2. Make sketches on the planes. 3. Extrude/revolve them (either adding or subtracting from the existing geometry). 4. Repeat until you have the right shape. 5. Add a load of chamfers to make it pretty.

From my experience people who heavily rely on LLMs are allergic to learning anything new (with the exception of learning new and improved ways to generate slop). They just 'want to get stuff done', even if it means staying in a local maximum forever.

So, steps 1-5 can be done by clicking (tools you recommend), or writing lines of script (OpenSCAD). Once you grok those steps by just doing it yourself, you quickly get to a point where an LLM is quicker at editing the text file that represents the steps to generate the model. Things like "Make the extruded face I labelled blahblah do xyz", and it's quite good. Even better: "Parameterize curve abc and generate this spread" or something. You get it.

For LLM-assisted bespoke model generation it's still fine if you specify a process to follow, and can "speak the language" (knowing 1-5).

This is no different than purevibe vs LLM-assistance, IMHO. What TFA refers to is a more end-to-end, no iterative process, with no single touchpoint script like OpenSCAD offers, so it's very much _not_ a collaboration and requires no knowledge of how CAD models are made.

But this thread is moreso about iterating on an OpenSCAD specification using LLMs.

Tell it to use the existing libraries. https://openscad.org/libraries.html, in particular BOSL2

I've one shotted a light saber hilt with threaded parts and it worked flawlessly.

Not OP but I just ask Claude Code to make me an openscad file. If I need changes I ask for them in plain english. If you are specific, it's not the quickest loop but it works. I usually ask it to parameterize the model enough so that I can quickly print small prototypes in my 3d printer. Once I am happy with the mini version I print the full-size model.

check this out: https://modelrift.com/blog/openscad-llm-benchmark LLMs are getting pretty good at OpenSCAD, especially if they work in agentic mode and can inspect intermediate results.

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