SolidCraft: open-source parametric CAD in Rust, what it can do today

What SolidCraft is and how it is built

The SolidCraft documentation calls it a parametric 3D CAD application written in pure Rust. The desktop app uses the egui and wgpu libraries, and the browser version is the same app compiled to WebAssembly, drawing with WebGPU or WebGL2.

The design choice that shapes everything else is the command layer. In SolidCraft, everything the user can do is a command with JSON parameters, and the toolbar, the dialogs, scripts, the CLI, the control channel and the MCP server all run those same commands. The docs spell out the consequence: anything you can click you can also script, test or hand to an agent.

The README states that SolidCraft is not affiliated with Autodesk, Dassault Systèmes, PTC, Siemens or any other CAD vendor; behaviour is designed from public documentation, general CAD conventions and user feedback.

The geometry kernel: SolidCore

The geometry kernel stores solids and computes booleans, fillets and shells. The SolidCore page describes SolidCore as a Rust port of SMLib, an open-source C++ geometry library released by NVIDIA, developed for use in SolidCraft and licensed under Apache-2.0. Stable releases do not use it yet; in the 0.40.0-rc.2 pre-release, modeling runs on solidcore as the only kernel, with no setting to go back.

Platforms: SolidCraft desktop and browser app

The downloads page lists a package for most systems:

• Windows An MSI installer, plus ARM64 and 32-bit installers and a portable zip that runs without installing.
• macOS A universal disk image for Apple silicon and Intel, signed with a Developer ID and notarized by Apple.
• Linux An AppImage, .deb, .rpm, Flatpak and Snap (sudo snap install solidcraft), with ARM64 builds and an Arch Linux package.
• Browser The web app at solidcraft.io/app, with no install.

Windows users should know that the Windows downloads are not code-signed yet. SmartScreen warns on first run, and the README tells you to choose More info, then Run anyway. The project says Windows signing through the SignPath Foundation is being set up. If you build from source, the getting started guide asks for stable Rust 1.95 or newer.

The browser version

The web app is the same application, not a viewer. The getting started guide gives the details that matter:

• Designs are saved in the browser's private file storage, which needs HTTPS or localhost.
• After the first visit the web app works offline, because the browser keeps a copy of it.
• A release candidate build and an edge build of the current main branch are available to try, but both can break, and a design saved in them may not open in the release.
• An embed mode shows the viewport, timeline, browser tree and joint controls inside an iframe, without the ribbon, file menus or start page.

Sketches and constraints in SolidCraft

Modeling starts with a sketch. According to the sketching guide, a sketch lies on an origin plane, a construction plane or a planar face. The capabilities list names lines, rectangles, circles, arcs, polygons, slots, ellipses, fit and control splines, conics and text, plus construction geometry, projection, trimming, fillets and chamfers.

Constraints include coincident, point on curve, horizontal and vertical, parallel, perpendicular, tangent, curvature (G2), equal, concentric, collinear, midpoint, symmetry and fix. Dimensions, including radius, diameter, angle and arc length, can be driven by parameters.

The solver is SolidCraft's own. Points that constraints fix relative to known geometry are placed by construction, and a Levenberg-Marquardt solver handles the rest, with the rank of its Jacobian giving the remaining degrees of freedom. In use, this shows up as two behaviours: over-constraining edits are rejected, and dragging re-solves the sketch every frame but rebuilds the model only once, when the drag ends. When you draw a shape and type its size, each value you type becomes a dimension.

Parameters and expressions

In the parameters guide, every dimension and feature input is a model parameter (d1, d2 and so on). User parameters are ones you add yourself, with a unit, an expression and an optional comment. You can name a value as you type it: typing width = 40 into a dimension creates a user parameter called width, and the input uses it from then on. When a parameter changes, the timeline rebuilds from the first feature that uses it. The README adds configurations to store variations of a design.

The parametric feature timeline

Solid features listed in the roadmap include extrude, revolve, loft, sweep, coil, fillet, chamfer, shell, draft, holes, threads, patterns, mirror and split. The capabilities list says the timeline rebuilds incrementally and that features can be edited, suppressed, renamed, reordered and deleted. Faces and edges keep their names through edits, so references survive changes.

The SolidCraft homepage demonstrates this with an enclosure driven by named parameters, whose height changes from 24 to 32 mm and rebuilds.

Beyond single parts, SolidCraft covers:

• Assemblies Components, joints, motion studies, contact sets, interference checks, mass properties and exploded views.
• Sheet metal Flanges, hems, fold, unfold and refold, material cutouts and flat patterns with DXF export, plus a plastic-enclosure subset of features.
• Rendering A Render workspace with GPU rendering, studio lighting, materials and image export, first released in 0.22.0. The capabilities list notes that HDRI, refraction and texture maps are not implemented.

SolidCraft file formats: import and export

The features page separates three kinds of file: native files keep editable features and history, STEP and IGES carry geometry, and mesh formats carry polygon meshes. The capabilities list gives the detail.

Two caveats matter. First, a mesh.convert command can rebuild only supported closed constant-section parts as parametric solids, so most imported meshes stay meshes. Second, design files carry a format number, and the roadmap warns that an older version refuses a design saved by a newer one. The 0.30.1 release notes state that designs saved in 0.30.1 use format 48 and do not open in 0.30.0 or older. Keep a copy before upgrading.

SolidCraft CLI, scripts and MCP for AI agents

Scripts and the headless CLI

The scripts documentation defines a script as a JSON list of commands, the same ones the UI runs:

{"commands": [
  {"command": "sketch.create", "params": {"plane": "XY"}},
  {"command": "sketch.rectangle.two_point", "params": {"p0": [0, 0], "p1": [40, 30]}},
  {"command": "solid.extrude", "params": {"distance": 20}}
]}

You run it with solidcraft-cli run script.json --out part.step. The CLI can also measure volume, area and centre of mass, export, and render PNG snapshots, so it fits in a build pipeline or test suite.

The MCP server

According to the MCP guide, SolidCraft speaks the Model Context Protocol over stdio (JSON-RPC 2.0). An agent models exactly like a person does: every tool runs the same engine commands and never opens a dialog. There are two modes. Headless, solidcraft-cli mcp runs its own design session with no window. Bridged, the server drives the running desktop app so you can watch the agent work.

The MCP page on solidcraft.io groups the tools: list_commands to discover operations, execute, batch and set_parameter to model, inspect_design, measure and body_topology to inspect, screenshot to view, and undo, redo, open, save and export. For Claude Code, the README gives a one-line claude mcp add command that registers solidcraft-cli mcp as a server.

Security settings worth reading before you connect an agent:

1. The desktop app opens a control channel on 127.0.0.1:27878 by default, reachable from the local computer only, with a fresh token per launch. Preferences can turn it off.
2. Tool calls reach files only inside the server's folders, such as the open design's folder, so ~/.ssh and other dotfiles are out of reach by default; --allow-path adds folders.
3. The MCP server runs on your machine, but your AI client may send prompts, tool output and screenshots to its provider.

AI is optional: the homepage states that SolidCraft works without a connected assistant. The app also has an agent chat, and the 0.30.1 release shipped security fixes for agent chat, lock files and API keys.

Project maturity, releases and limits

SolidCraft is young, and the project says so. The documentation states that sketching, solid modelling, parameters, components with joints, sheet metal and a plastic-enclosure subset work, while surfaces, drawings, CAM and simulation are deferred. The README reports that 75 of 76 public reference parts match their analytic or FreeCAD-computed volume, area, centre of mass and bounding box, with the other one a tracked bug. The capabilities page adds that these checks do not establish complete geometric or workflow equivalence.

Current gaps, per the roadmap:

• Drawings In progress on a branch and not in the app yet. Today you can export the current view as a DXF.
• CAM There is no CAM in SolidCraft yet.
• Surfacing Patch, trim, blend and match exist; the rest of the surface toolset is planned.

Releases ship daily as numbered versions with nightly pre-releases in between, and features are not tied to a release or a date. As of early November 2026, the 0.40.0-rc.2 notes say the stable release is still 0.30.1. That pre-release lists 31 known-failing tests, warns that variable-radius fillets may fail on solidcore, and says the team has not measured speed or quality against 0.30.1. Treat the 0.40 candidates as a test track and the 0.30 line as the one for real work.

SolidCraft licence and who it fits

SolidCraft is licensed MIT OR Apache-2.0 at your option, and the roadmap states that versions already released stay available under those licences permanently.

SolidCraft fits:

• Developers who want CAD they can script, test and diff, because every action is a JSON command and the CLI can measure and export.
• Teams experimenting with AI agents for mechanical modeling, with a local MCP server and documented file-access limits.
• Makers who design simple parts, enclosures and sheet metal, and want a free tool on Linux, Windows, macOS or in a browser.

It does not fit yet:

• Work that needs production drawings, CAM toolpaths or simulation, which the project lists as deferred.
• Teams that need long-term file stability across versions, given format changes and the kernel switch in 0.40.
• Organisations that only allow code-signed Windows software, until signing goes live.

If you are comparing options, the CAD and 3D tools category on iThub lists other parametric and mesh modelers.