Mesh2cad MCP server

mesh2cad

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Turn 3D meshes (STL/OBJ/PLY) into real, editable CAD (STEP): fitted planes, cylinders, spheres, cones, and constant-radius fillets instead of triangle soup. CLI + MCP server for AI agents. MIT, pure Python on top of OpenCascade.

Left: 21k-triangle mesh with 0.1 mm noise. Right: the STEP mesh2cad writes: 10 planes + 2 cylinders, max deviation 0.05 mm from the true part.

Install

pip install mesh2cad              # CLI + STEP
pip install "mesh2cad[mcp]"       # + MCP server
pip install "mesh2cad[cadquery]"  # + run/verify generated CadQuery scripts

OpenSCAD scripts are plain text. Verifying one needs the openscad program (openscad.org); it is not a Python dependency. Without it the .scad file is still written.

Use

mesh2cad convert part.stl -o part.step --tol 0.1 --report report.md
mesh2cad report part.stl --json

--tol ≈ the noise / accuracy of your mesh in model units (default 0.1 % of the bounding-box diagonal).

Output: STEP + fidelity report: method (exact / faceted-hybrid / faceted), face types, solid validity, two-sided Hausdorff / RMS deviation, volume error, % area per surface type.

Editable parametric CadQuery script

For simple prismatic parts mesh2cad can also write a CadQuery Python script where every dimension is a named parameter, so you change a number and re-run instead of editing B-rep faces:

mesh2cad convert bracket.stl --cadquery bracket.py   # add -o bracket.step to also write STEP
python bracket.py                                    # -> bracket.step

# --- parameters ---
base_x           = 40.0  # base length (X)
base_y           = 30.0  # base width (Y)
base_t           = 6.0  # base thickness (Z)
...
hole_1_d         = 6.0  # diameter
hole_1_x         = 0.0
hole_1_y         = 0.0
hole_1_csk_d     = 12.0  # countersink diameter
hole_1_csk_angle = 90.0  # countersink angle

Make the hole 2 mm bigger: set hole1d = 8.0 and run it again. A plate or block whose four vertical corners share one radius also gets filletr and .edges("|Z").fillet(filletr), so the same edit grows the round.

A hole or boss on a side face uses the same kind of parameter. This is the block below (60×40×36, an Ø8 hole through X, an Ø6 hole 12 deep opening on +Y, an Ø10 boss 8 tall on +X):

Shortened. The full README is on GitHub.