9 easy steps for llama.cpp, a local model, Freecad (and pi coding agent) to generate solid objects that sound mechanically good and can be also be 3D printed/milled

install/download llama.cpp, Freecad, your favourite gguf model - possibly with multimedia image reading capabilities (I've used Qwen3.8-27B-UD-Q4_K_M and relative mmproj-F16 quantized by Unsloth), uv (, pi.dev)

if using pi coding agent as modelling assistant, write into the file ~/.pi/agent/mcp.json:

if using llama-server as modelling assistant, write into a file called freecad_mcp.json:

$ pi update; pi install npm:pi-mcp-extension run pi then into pi issue the command: /mcp:start freecad

start llama-server as usual adding the option --mcp-servers-config /your/path/to/freecad_mcp.json

Verify that freecad_* tools are available under llama-server webui > Settings > Tools > Server, eventually allowing them to run without asking permission; also under webui > Settings > Agentic > Agentic turns increase the value to something like 99

start llama-server as usual also adding, if the model has multimedia capabilities, the option to load the visual add-on using: --mmproj name_of_the_mmproj.gguf in order for the local model to read screenshots from freecad and to verify the correctness of performed geometric operations

start Freecad, select the "MCP Add-on" workbench, click on "Start RPC Server" and/or "Auto-Start Server"

STEP 8: into llama server webui or into pi write something like the following prompt:

in freecad generate a cube with a 5 spokes star shaped hole going through it from top to bottom

In freecad create a new project called "double smooth gears". Into this project design 2 equal gears with 20 spokes each that could be put in close contact with those of the other gear to rotate and counter-rotate one gear against the other one. The spokes "hills" have to be rounded and so the corresponding spokes "valleys" should be analogously; sort of a sinusoidal curve on a circular path.