Use SpeakCAD from ChatGPT, Claude and other AI assistants
Assistants are good at understanding what you need and bad at producing a file that prints. The SpeakCAD connector splits the work: the assistant finds or describes the part, SpeakCAD builds the dimensioned model and the STL, 3MF or G-code.What the connector does
MCP (Model Context Protocol) is the standard ChatGPT, Claude and other assistants use to talk to outside tools. The SpeakCAD server exposes four of them:
- search_models looks through the library of generate-to-fit parts and the maker marketplace, and returns the matching models with their pages.
- get_model returns one model in detail: what it is, the example prompt with its real dimensions, a preview image.
- start_custom_part turns your description and measurements into a link that opens SpeakCAD with the prompt filled in.
- get_pricing gives the assistant the current plans, so it quotes the right price.
What it does not do
The connector does not generate geometry inside the chat and does not return an STL. Your part is generated in your own SpeakCAD account, where you can see it, turn it around, check the dimensions and correct it before spending a download. That is deliberate: a file you have not looked at is a failed print waiting to happen.
Generating and downloading use your plan's credits, exactly as on the site. The connector itself is free and works without an account.
Why not let the assistant write the model itself
Assistants will happily write OpenSCAD or describe a shape, and the result usually needs a CAD tool, a fix for a non-manifold mesh, and a slicer. SpeakCAD compiles the model in the browser, applies FDM design rules (wall thickness, clearances, a flat base), shows it in 3D, and exports a watertight file, or G-code for your exact printer. The assistant is the front door; the editor is where the part gets right.
Good requests
Give measurements in millimetres and say what the part mates with: "an enclosure for a 70 x 50 mm PCB with four M3 holes on a 62 x 42 mm pattern, a USB-C cutout on the short side, 2 mm walls and a snap-fit lid". The assistant passes all of it along, and the numbers are used exactly.
Invite a friend while you are at it
Every SpeakCAD account has an invitation link on its plan page. A friend who subscribes from it gets extra credits, and so do you, more on a higher plan.
- 1Copy the connector addressThe SpeakCAD MCP server is at https://speakcad.com/api/mcp. It needs no key and no login: it only reads the public catalogue.
- 2Add it to your assistantIn Claude: Settings, Connectors, Add custom connector, paste the address. In ChatGPT: Settings, Apps and connectors, turn on developer mode in the advanced settings, create a connector and paste the address. Any other MCP client works the same way, with the Streamable HTTP transport.
- 3Ask for a partDescribe what you need: a case for a Raspberry Pi 5 with a fan cutout, a hook for a 40 mm pipe. The assistant searches the SpeakCAD catalogue and shows the models that fit.
- 4Open the link it gives youA catalogue model opens on its page; a custom part opens SpeakCAD with your description already typed. The model renders in your browser, on a phone or a computer.
- 5Adjust and downloadChange any millimetre by chat or by typing a number, then download STL or 3MF, or G-code sliced for your printer on Pro.