SolidCraft: open-source parametric 3D CAD in pure Rust, MCP included

Pick a free parametric CAD that actually ships and you hit the usual walls: FreeCAD does everything but takes a week to learn, and Onshape’s free tier keeps your design files on someone else’s cloud. SolidCraft is an open-source parametric 3D CAD written in pure Rust (Apache-2.0): sketches, constraints, a feature timeline, assemblies and sheet metal, with desktop, browser, CLI and a built-in MCP server all running the same command set — and the MCP means an AI agent can model parts directly in the kernel. The repository was created on October 7, 2026 and crossed about 11,000 stars in three weeks (as of October 27, 2026), with commits landing the same day. The project’s own bar is “early but usable”: 75 of 76 public reference parts match analytic or FreeCAD-computed volume, area, centre of mass and bounding box.

Core features

• Parametric feature timeline: sketches, constraints and a feature tree where one dimension change rebuilds everything; in the official demo a Raspberry Pi 4 case goes from 24 mm to 32 mm and the standoff pattern, cut-outs, vents and engraving all follow.
• A complete modeling set: extrude, revolve, sweep, loft, fillet, shell, draft, hole, thread, pattern, mirror, split and combine; sketches take splines and text, backed by a purpose-built constraint solver.
• Assemblies and sheet metal: assemblies carry motion simulation, interference checking and mass properties; the sheet-metal module does bend relief and unfold, with plastic-enclosure features alongside.
• Format coverage: STEP, IGES, 3MF, STL, OBJ and glTF in and out, plus URDF export for robot simulation.
• One kernel, four runtimes: desktop builds for Windows/macOS/Linux, the browser app at solidcraft.io, a CLI and the built-in MCP server all speak the same commands, so scripting and AI-driven modeling need no second tool.
• Checkable geometry: the repo ships an “oracle” set of 76 public reference parts, each verified against analytic or FreeCAD-computed volume, area, centre of mass and bounding box.

Typical use cases

• Modeling for 3D printing: parametric brackets, cases and jigs exported as STL/3MF straight to the slicer, with zero install via the browser version.
• Rebuilding legacy parts parametrically: turn a fixed-dimension STEP file into a constrained model once, then change specs without redrawing.
• Letting an agent model: hand Claude Code or another MCP client an instruction like “a 58×49 mm plate with M2.5 holes in the corners” through the built-in MCP server — useful for template and batch parts.

Quick start

The browser version needs nothing installed: open solidcraft.io/app and start sketching. For desktop, grab an installer from the download page (Windows, macOS and Linux, plus Snap). The builds are not code-signed yet: on Windows choose “Run anyway” past SmartScreen, on macOS right-click and Open the first time. The CLI and MCP ship with the desktop app, and examples/demo/ in the repo has the script that reproduces the official demo.

Summary

What makes SolidCraft worth watching: a geometry kernel, a constraint solver, four runtimes and MCP support all live in one pure-Rust repository — and 11,000 stars in three weeks says the demand is real. It is genuinely early, though: the site itself scopes it to simple parts, one of the 76 reference parts fails verification, installers are unsigned, and the 3,723 open issues (as of October 27, 2026) show how long the defect list still is. Heavy mechanical users should stay on FreeCAD or a commercial tool for now; if you model simple parametric parts or want to try AI-driven CAD, start in the browser. Apache-2.0, Rust. A complementary route to agent-generated models is text-to-cad, which wraps OpenCascade as a plugin for coding agents — SolidCraft’s built-in MCP and that plugin approach solve the same problem from opposite ends.