Claude and Fusion360 MCP - Amazing! New plugin coming soon!

I figured I'd share a little side project I've been working on

I dabble in 3D printing, so naturally I taught myself CAD. Lately I've been experimenting with Claude Code and the Fusion 360 MCP.

It's shockingly good. But, the Fusion MCP only exposes 3 tools, even though there's an entire API infrastructure sitting behind it.

Those three tools are a thin wrapper over the entire Fusion Python API. One of them runs arbitrary Python inside your live CAD document. So "3 tools" is really every sketch, extrude, fillet, hole, pattern, mirror, export, and parametric constraint Fusion has ever shipped. You just have to know how to reach them. Three doors, and the whole building is behind them.

The catch is that nobody has mapped the building. The API is huge, the docs are thin, and a lot of it fails in quiet, confusing ways. So that's what I've been doing with Claude: mapping it, one real design at a time.

As we work though new designs, Claude logs what worked, what broke, and why, into running document that's being used to build the skill and a plugin. The next design starts smarter than the last. It's a recursive loop. When I started, I had to walk Claude through a design step by step. Now I can hand it "design a center console organizer for a 2017 Jeep Wrangler," and it researches the real dimensions, then models the whole thing. The last one took 28 minutes, 13 of which was research. I wasn't involved at all.

A few of the things we discovered and logged along the way:

A self-intersecting sketch doesn't throw an error. Fusion silently reports it as two valid shapes and extrudes garbage. The only tell is a profile count of 2 where you expected 1. So now Claude asserts the count before every extrude.
Setting a dimension to a parameter name can silently fail to bind. The API swears the sketch is fully constrained. The UI knows it isn't. That one cost real time to catch, and now it's a documented workaround.
Undo treats your last script as one atomic transaction. If that script added parameters and geometry, undo wipes both without a word. So every script we write is idempotent instead.
Internal units are centimeters, not millimeters. Ask the docs the wrong way and they return "success" with empty data. The official axis mapping for one of the sketch planes is just plain wrong, and we proved it with a test point and corrected it.

The one that turned into our best safety net: volume math as a lie detector. After every feature, Claude computes what the volume should change by and compares it to what actually happened. Across 35+ features and multiple designs, it's matched to under a cubic millimeter every time. When the geometry is wrong, the number doesn't match, and we catch it before it ever reaches the printer. Screenshots lie about orientation. Math doesn't.

Right now we're on print-in-place hinges and properly clearanced sliding lids, all driven from a single parametric clearance value.

I'm aiming to submit the skill and plugin for review and publishing by the weekend, with a full YouTube walkthrough: how to set it up, where to grab the skills, how to install and use everything. I'll drop the GitHub here when it's live.

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Claude and Fusion360 MCP - Amazing! New plugin coming soon!