MAmarkcheno·Mar 31, 2026
I just ran into this today: https://github.com/gumyr/build123d - seems like an LLM should have no problem writing python code...
In Open source CAD in the browser (Solvespace)gumyr
build123d
Python2023–2026
gumyr / build123d
build123d
A python CAD programming library
16Distinct people
24Mentions
1Explicit recommenders
3.7KGitHub stars
What to know before exploring
What it is
A python CAD programming library
GitHub
Where it is used
- WorldKinetics — WorldKinetics uses build123d to generate solid geometry and create STEP/STL exports. It is part of the system that turns a user’s request into downloadable CAD outputs. Source
What people are saying
Yes, absolutely. It was where GIMP still is now, for artists. It's definitely been idiosyncratic (if not solipsistic), and still has IMO some maddening features. And it still…
bemusedthrow75 used a recommendation phrase. One indexed comment matches. This is a phrase match, not a verdict.
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Also in these discussions
- cadquery/cadquery · linked in 3 of the same discussions
Mentioned in the same Hacker News threads. That is not proof they are substitutes.
This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.
No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.
Mentions over time
HN mentions by year24 dated mentions
Observed mentions: 2023-06-16 10:35:40 UTC to 2026-03-31 16:57:13 UTC.
* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| 2023 | 2023-01-01 00:00:00 UTC | 2024-01-01 00:00:00 UTC | 6 | 2 | 4 |
| 2024 | 2024-01-01 00:00:00 UTC | 2025-01-01 00:00:00 UTC | 5 | 0 | 5 |
| 2025 | 2025-01-01 00:00:00 UTC | 2026-01-01 00:00:00 UTC | 8 | 2 | 6 |
| 2026 (partial) | 2026-01-01 00:00:00 UTC | 2027-01-01 00:00:00 UTC | 5 | 2 | 3 |
What Hacker News says
24 sourcesBuild123d: A Python CAD programming library
153 points · Open discussionSome other open source 3D CAD tools:
Code-based
- CadQuery - https://github.com/CadQuery/cadquery/
- build123d - https://github.com/gumyr/build123d
- OpenSCAD - https://openscad.cloud/openscad/
GUI (browser-based)
- Cadmium (abandoned, cool idea) - https://mattferraro.dev/posts/cadmium
In Dune3d: A parametric 3D CAD applicationI'm pretty happy with build123d these days https://github.com/gumyr/build123d
In FreeCADBuild123d is a Python-based parametric BREP modeling framework for 2D and 3D CAD
4 points · Open discussionCould 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
Read the rest
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
worth also looking at cadquery, build123d and similar
https://github.com/gumyr/build123d
In OpenSCAD is kinda neatBuild123d (A Python CAD programming library) Roadmap
1 points · Open discussion>OpenSCAD however fails spectacularly for any kind of complex filetting situation when compared to tools like Fusion or even FreeCAD (FreeCAD's UI is an abomination though).
build123d[1] is based on the same kernel as FreeCAD and has full support for complex filleting situations. Furthermore it also has first class support for 1D and 2D primitives which enable a more flexible design approach.
> The morphological ops in OpenSCAD (minkowski type stuff) are a very poor substitute to real fillets, and are extremely slow (underlying algos are all polynomials in number of triangles) when your objects get complex, and they are global operations, it is extremely hard to limit their action to a localized part of your object.
Agreed.
> Another thing that's a real pain in OpenSCAD: you cannot "probe" (measure) your existing object at a certain stage
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, grab the result of that measurement and re-use it in the rest of the code. MAJOR limitation.
This is another area where build123d excels. You can create a line and query its length. You can create a face and query its area, position, size, bounding box, etc. You can select parts of a solid and perform operations on them (like a chamfer/fillet, or use them as a reference for positioning). You can query the geometric type of any topological entity; e.g. is this curve linear, a circular arc, elliptical, or a spline?
build123d is IMHO easily one of the most powerful CAD packages that are not well known by a wide audience (owing in part to its ~3 year history). OpenSCAD is a fantastic tool; it was my introduction to CodeCAD and I used it for years. Therefore, my objection isn't to OpenSCAD itself, but to the limitations inherent in any single tool -- and in this case, those limitations are quite significant.
[1]: https://github.com/gumyr/build123d and docs https://build123d.readthedocs.io/en/latest/
> For the latter, if you already know Python, you might want to consider (Open)PythonSCAD
If you know python then build123d(/cadquery) are also options:
https://github.com/gumyr/build123d
In Drafting Software RecommendationBuild123d: A Python CAD programming library
4 points · Open discussionalso have a look at https://github.com/CadQuery/cadquery
(and https://github.com/gumyr/build123d)
python, but more pythonic then openscad
In Design for 3D-PrintingThere is build123d too
https://github.com/gumyr/build123d
In FidgetAlso see https://github.com/gumyr/build123d (which is closely related to CadQuery, my understanding is it's successor). I used b123d for a project this year and it turned out perfect. When I need to make a change, editing some version controlled py and watching the model update is very satisfying.
Best resources to get a feel of why programmatic parametric modeling is so interesting:
https://cq-warehouse.readthedocs.io/en/latest/fastener.html
https://bd-warehouse.readthedocs.io/en/latest/index.html
In CADing and 3D printing like a software engineerI really like build123d[1], which is based on CadQuery. There are a few nice IDEs for it and to make it simple: It's python based code-based CAD.
[1]https://github.com/gumyr/build123d
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