SolidCraft is an open-source parametric 3D CAD application written entirely in Rust, targeting desktop (Windows, macOS, Linux), browser (via WebGPU/WebGL2), and headless automation through an MCP server that lets AI agents drive the modelling pipeline. The pitch is straightforward: sketch, constrain, extrude, and watch your model rebuild when you change a parameter. The ambition is less straightforward — this is a from-scratch challenge to the FreeCAD/Fusion 360/SolidWorks stack, built on a constraint solver the developers wrote themselves. The feature list reads like a mid-career commercial CAD tool compressed into an early release. Sketches support lines, rectangles, circles, arcs, polygons, slots, ellipses, splines, conics, and text, with construction geometry and projection. The constraint solver uses loci intersections and rigid-cluster decomposition (citing Owen 1991 and Fudos–Hoffmann 1997) for exactly-solvable geometry, with Levenberg–Marquardt handling the rest. The parametric timeline supports extrude, revolve, sweep, loft, fillet, chamfer, shell, draft, holes, threads, patterns, mirror, split, combine, and move. There's sheet metal with flanges, hems, fold/unfold, flat patterns, and DXF export. Assemblies with joints, motion studies, contact sets, and interference detection. STEP, IGES, 3MF, STL, OBJ, and URDF export. The validation story is concrete: 75 of 76 public reference parts match their analytic or FreeCAD-computed volume, area, centre of mass, and bounding box, with the single failure tracked as a known bug. That's an unusually rigorous self-assessment for an early-stage open-source project. The developers are explicit that this does not establish complete geometric or workflow equivalence — a level of honesty that earns trust. The MCP server integration is the forward-looking bet. A demonstration by @0xlillith shows SELENE, a scientific rover built entirely through the MCP server — 3,323 editable timeline steps that rebuild with no errors. This is the most interesting design decision in the project: making the CAD kernel a first-class automation target means AI agents can generate, iterate, and validate physical designs programmatically. Whether this matters depends on whether LLM-driven design workflows actually converge on useful geometry, but the infrastructure is there. The Rust-native stack (egui + wgpu) means the app runs without heavy runtime dependencies, and the browser version works through the same codebase via trunk/WASM. Cross-platform coverage is thorough: x8664 and ARM64 on all three desktop OSes, plus Flatpak, Snap, AppImage, .deb, and .rpm on Linux. 3Dconnexion SpaceMouse support via direct HID reads is a nice touch for the target audience. The honest constraints: downloads aren't signed yet, so Windows SmartScreen and macOS Gatekeeper require manual overrides. The project self-describes as "early but usable for simple parts." The feature list in docs/features.md and the roadmap in ROADMAP.md are the real scope documents. This is not yet a FreeCAD replacement for complex assemblies or a SolidWorks competitor for production workflows — it's a technically impressive foundation with a clear trajectory. What makes SolidCraft worth watching isn't any single feature — it's the combination of pure Rust performance, browser deployment, MCP-driven automation, and a constraint solver built from the academic literature rather than wrapped around an existing kernel. If the project sustains momentum, it could become the first CAD tool where AI-agent-driven design is a native workflow rather than a bolted-on integration.
