OwlCAD brings parametric CAD and AI-powered design to the browser

Spare Matter Corp has released OwlCAD in beta, a parametric CAD program for designing for 3D printing that runs entirely in the browser. All users need is a browser, with no installation or account required. The geometry engine processes models locally on the user’s computer, so operations do not have to wait for a server response. The full editor is free, including all export formats and the right to sell prints and files without licensing fees. AI-powered features, along with agent access through an MCP server, are included in the Pro plan at $12 USD per month or $120 USD per year.

AI-based 3D generators have been able to produce shapes that look convincing on screen for some time. The problem starts when a hole needs to be widened by 0.4 mm, because a triangle mesh does not remember that it was ever a hole. OwlCAD promises something more modest and, at the same time, more practical: a model that comes with live dimensions and an editable history.

How Parametric Generation Works in OwlCAD

When a user describes a part, the parametric mode returns a node tree made up of basic solids, Boolean operations, and transformations, with every dimension remaining editable. Changing 30 mm to 32 mm rebuilds the entire part, and the change can be undone like any other edit. The same applies to the Modify with AI feature, whose changes are added to the model history instead of being permanently baked into the geometry. The company puts it simply: a mesh remembers what something looks like, while a parametric model remembers how it was made. For someone printing an enclosure for a specific circuit board, this means the part can be adjusted to match the physical hardware. Sculptural mesh generation remains available with a single click when the goal is simply to make a shape look right.

Underneath the AI layer is a complete editor. It offers constraint-based sketches, extrude, revolve, sweep, and loft operations, fillets and chamfers on individual edges, assemblies with mates and bills of materials, variables and formulas, and 33 generators, including gears, threads, hinges, enclosures, and Gridfinity containers. The print-focused layer adds fit presets ranging from tight to loose, overhang, thin-wall, and watertightness checks, printer profiles, automatic orientation, and estimates for mass and cost.

Import supports STL, 3MF, OBJ, STEP, DXF, SVG, and OpenSCAD files, which can be opened as editable trees. Export is available in STL, 3MF, OBJ, GLB, STEP, DXF, and SVG formats. The preview is rendered using React and Three.js, Boolean operations are handled by Manifold compiled to WebAssembly and running in a separate Web Worker, while STEP export is powered by OpenCascade. The company itself indicates the products it considers comparable, listing TinkerCAD, Onshape, Fusion 360, FreeCAD, SelfCAD, and OpenSCAD alongside OwlCAD on its website.

MCP Server for AI Agents

The hosted MCP server allows Claude Code, Claude Desktop, Cursor, or any MCP client communicating over HTTP to build and edit models without a CAD application being installed anywhere. Its 29 tools allow an agent to build a model tree, render a preview and inspect its own work, check overhangs and whether a model fits within the build volume of a specified printer, calculate volume, filament usage, and cost, detect collisions in an assembly, and split an oversized part into two halves with connections using dowels, slots, locating pins, or screws. Both halves remain parametric. Access requires the Pro plan but does not consume AI credits. Limits include 2,000 calls per token per day, 100 new projects per account per day, and exports of up to 8 MB or 200,000 triangles.

The documentation also contains a warning about rotations, since angles are specified in degrees, while a tree stored in radians will render with almost no rotation. As the authors point out, this error does not produce an obvious warning. An agent that confuses the units can therefore receive a valid-looking response while producing a wrongly rotated part.

OwlCAD is targeting a space that is rarely addressed directly: the point between an idea and a file ready for a slicer. As evidence, the company presents a recording of a real session from its own agent benchmark. Gemini 3.6 Flash was tasked with building an 80 × 60 × 5 mm mounting plate with four 4 mm-diameter through-holes, each positioned 8 mm from two of the edges. The agent first read the solid-model schema and conventions, then ran an evaluation that confirmed a watertight solid with the specified dimensions. It then performed a printability check showing zero overhang and a minimum wall thickness of 5 mm, followed by a measurement estimating that the part would consume 18.5 g of PLA.

As a demonstration, the task is modest, making it difficult to draw conclusions about how the agent would behave with a more complex assembly involving hinges or threads. It does, however, demonstrate a useful workflow in which the machine reads first, verifies its work next, and only then produces a result that a human can open and modify. The finished plate consists of six elements in the model tree and can be opened in the editor without creating an account.