Code2Form: design a 3D part as code, and hand it to an agent

A classic CAD tool records a sequence of clicks. Code2Form records a text: a 60 × 40 × 20 mm cube, a cylinder subtracted to drill a hole, a variable "wall = 2" reused wherever thickness matters. Change the variable, and the whole part follows.

Three practical consequences. A variant means changing a number, not redrawing. The file can be compared from one version to the next and kept in Git, with a history that says what changed. And parameters declared in comments become sliders, dropdowns and checkboxes in the app, with presets saved next to the part: someone who does not read code can produce their own variant.

Code2Form opens .scad files as they are, a common format for this kind of design. Its compatibility is checked against the reference implementation (release 2021.01) on the 86 examples and libraries it ships: the same syntax tree, the same CSG tree, the same output, and the same volumes on every exportable model but one. These results are frozen in the repository's tests and checked again on every change.

Boolean operations go through Manifold, a robust geometry library, and STL and 3MF exports are checked with PrusaSlicer's own loader. The pause(z, message) function adds a print pause at a given height, to drop a magnet or a nut into a cavity before it closes; the 3MF carries it to PrusaSlicer, and the layer view lets you move it with the mouse.

The repository holds a complete example, Grogu: a XIAO ESP32-S3 board that listens (an INMP441 microphone), speaks (a MAX98357A amplifier and a speaker), moves (a DRV8833 driver and a motor) and feels a touch (a copper plate).

Each component is a .c2f file that draws it, with its pins, mount holes and ports declared in comments, at their position in millimetres. A circuit file (.c2fc) places the components and wires their pins: 23 wires, laid in order, power first.

Before soldering, Code2Form checks the wiring: a supply above what a pin accepts, two supplies tied together or to ground, a supply or ground left open, a do-not-connect pin that is connected. In the example, the 5 V rail feeds the amplifier and the motor driver, and the microphone alone takes 3.3 V: a mistake there is flagged before the soldering iron, not after.

The printed plate that carries it all repeats no dimension: it names its circuit and takes its standoffs, holes and openings from it (the USB-C port, the speaker grille, the microphone hole). Move a board in the circuit, and the plate follows. The app then shows the components and their wires in colour, and an assembly mode walks through the wires one by one, keeping track of progress.

This is the part that interests us most. The c2f mcp command exposes Code2Form as an MCP (Model Context Protocol) server, the protocol that lets an agent such as Claude Code use a tool. One line adds it: claude mcp add code2form -- c2f mcp.

The agent does not drive the open app: it works on files. It renders a part and gets back either the error with its line and column, or the volume and bounding box. It lists the parameters, gets a PNG picture from the angle it chooses, exports STL, 3MF, SVG or DXF. On the electronics side, it lists the library's components, reads their pins, checks a circuit, and gets a picture of it, the wiring list and the bill of materials.

The picture matters more than it seems. As we wrote in our Claude Code best practices, an agent that can check its work fixes its mistakes before showing them to you. A render without errors does not tell you a hole is on the right side; a picture does. For the circuit, the check is even sharper: check_circuit says whether the build is fit to solder, and the agent keeps fixing until it is.

The decision stays human. The agent proposes a checked circuit and a wiring list; a person opens the file in the app, looks at it in 3D, starts the print and solders. It is the rule from our other articles: the agent prepares, the check is automatic, and the costly action stays with a person.

Version 0.3 downloads for macOS 11 and later: one app for both Apple silicon and Intel Macs, and the c2f command line separately. The app is not notarized by Apple yet: on first launch macOS blocks it, and you allow it once in System Settings, Privacy & Security. On Windows and Linux, it builds from source with Rust 1.85 or later; the tests run on all three systems.

Known differences are documented: one projection() case that keeps open holes the reference implementation fills (0.3% of the volume on the example concerned), some fonts at large sizes that differ by a fraction of a percent, and edge cases with NaN and infinite values. A component's pins are fixed numbers that do not follow its parameters yet, and some library dimensions are estimated, which each file states.

It is young software: the first public release is dated 21 October 2026. For a part going into production, keep your usual checks. For a prototype, a jig or a demonstrator's enclosure, it is exactly on its ground.

Code2Form, repository and documentation: README, electronics guide, Grogu example. Source code, electronics guide.

Code2Form 0.3.0, release notes of 22 October 2026: downloads, notarization, known limitations. Release notes.

Model Context Protocol, official documentation. modelcontextprotocol.io.