Free STL to STEP converter that recovers real CAD geometry

mesh2cad turns a triangle mesh (STL) back into a solid model: real planes, cylinders and chamfers in a STEP file, plus optional editable CadQuery or OpenSCAD code with the dimensions as parameters. Not just triangles wrapped in a STEP file.

30 second quickstart

pip install mesh2cad
mesh2cad convert part.stl -o part.step

Run mesh2cad convert --help for the CadQuery and OpenSCAD export options. To use it from an MCP client, add the server command mesh2cad mcp (install with pip install "mesh2cad[mcp]").

Honest limits

• Works best on mechanical parts made of planes, cylinders, cones and chamfers (brackets, holders, printer parts).
• Example: mesh2cad convert bracket.stl --cadquery bracket.py
• Organic shapes (figurines, scans, sculpted surfaces) are not recovered as exact surfaces.
• Every export passes a self check against the original mesh (deviation and volume error). If a part fails, mesh2cad refuses and tells you why instead of giving you a wrong model.
• On our 6 Prusa printer test parts: exact STEP for 6 of 6, editable CadQuery/OpenSCAD for 6 of 6 (v0.15.0).

FAQ

How do I convert STL to STEP for FreeCAD or Fusion 360?

Run mesh2cad convert part.stl -o part.step, then open the STEP in FreeCAD (File, Open) or upload it in Fusion 360. Because faces are fitted as real surfaces, you can select a hole or face and edit it, unlike a mesh converted with "mesh to solid".

Is it different from FreeCAD's Part, Create shape from mesh?

Yes. That tool makes one flat face per triangle. mesh2cad fits primitives, so a cylinder becomes one cylindrical face.

Can I get an editable parametric model?

Yes, for parts that pass the check: see STL to OpenSCAD and CadQuery.

Does it upload my files anywhere?

No. It runs locally on your machine.

What does it cost?

Nothing. It is open source on GitHub and PyPI.

mesh2cad is free and open source (see the GitHub repository for the license). Found an STL it handles badly? Open an issue with the file.