Physpace

Language models write CAD as marimo notebooks: one feature per cell, and every step verified.

[Physpace @physpacedev]

Physpace is live on @RobinhoodApp

SimpleCADAPI lets coding agents write real, editable CAD as plain Python: one feature per cell, every dimension a named parameter, every step verified.

CA: 0x014ca55ebac6549441b98feed7176e50c0d2ac15

[Physpace @physpacedev]

sca edit opens a browser editor over your notebooks. Click a face or an edge and it writes a scad.ql selection cell your coding agent reads from disk.

[Physpace @physpacedev]

Install SimpleCADAPI by hand:

pip install simplecadapi
uv add simplecadapi
pipx install "simplecadapi[editor]"

The [editor] extra adds sca edit, the code-first editor. Then sca example u_link copies a bundled example workspace out to open in it.

[Physpace @physpacedev]

Ribbed L-bracket: 2 user turns, 49 tool calls. A legacy script rebuilt as feature blocks with a volume delta under 0.1%, keeping the interface.* tags the Gmsh/CalculiX pipeline selects faces by.

[Physpace @physpacedev]

Every case in the README is a real, reproducible session, replayed in full next to the exported model. Three single-part sessions ↓

[Physpace @physpacedev]

Parametric flange plate: 2 user turns, 66 tool calls. Every dimension a named parameter, edge-selection cards printed before each fillet, and feasibility guards on the bolt pattern.

[Physpace @physpacedev]

Robotic-arm U-link + motor mount: 15 user turns, 601 tool calls. A circular profile swept into a U, motor sockets cut with spheres, and a mounting face with a deterministic name the query language can index.

[Physpace @physpacedev]

Simulation survives the next revision.

One package exports AP242 STEP, editable FreeCAD and MJCF. Boundary faces keep their interface.* tags through Gmsh into CalculiX, so the load case finds its faces again after every change.

[Physpace @physpacedev]

Assemblies are constraints, solved strictly. The integrated BLDC joint actuator: 29 components, 51 constraints, 74 solids and a 20:1 two-stage planetary.

[Physpace @physpacedev]

Buyback and burned.

https://t.co/HtpSyxsWz9

[Physpace @physpacedev]

Seven ideas, each shown on a real model from the repository. A scroll through https://t.co/tFZ1zW79cV.

[Physpace @physpacedev]

Name the edge, not its index.
Change the intent, not the geometry.

[Physpace @physpacedev]

In the recorded flange session in the README, a PCD of 88 was rejected live by the guards, and 85 was excluded for fillet tangency.

[Physpace @physpacedev]

Change the intent, not the geometry.

Every dimension in a SimpleCADAPI notebook is a parameter and every assumption is a guard. Change BOLT_COUNT and the notebook rebuilds; push the bolt circle past the rim and the guard refuses first ↓

[Physpace @physpacedev]

Each step is a full notebook run with overrides. Raise the bolt count to 8 and the model has 17 faces; at 12 it has 21. Nothing is redrawn by hand.

[Physpace @physpacedev]

On the site's flange_plate.py: 4 × ⌀11 holes on a PCD of 84.5 mm. The guard checks the web left at the rim, OD/2 − PCD/2 − d/2 = 2.250 mm, against a 2.0 mm minimum. Result: 13 faces, 100,856.7 mm³.

[Physpace @physpacedev]

Dexpaid.

[Physpace @physpacedev]

Change the intent, not the geometry.

Every dimension in a SimpleCADAPI notebook is a parameter and every assumption is a guard. Change BOLT_COUNT and the notebook rebuilds; push the bolt circle past the rim and the guard refuses first ↓

[Physpace @physpacedev]

Errors are feedback, in numbers an agent can act on.

[Physpace @physpacedev]

Agents cannot click. So QL selects edges by what they are, asserts exactly(2), and tags the faces a fillet makes: fillet.flange_edge, not face number 14.

[Physpace @physpacedev]

A SimpleCAD model is a marimo notebook: a plain .py file and the only source of truth.

Each feature is one cell, each dimension a scad.var. An agent edits text, the BRep follows cell by cell, with a fact card after every step.