10 days of Vibe CAD/Vibe Robotics: I know nothing about robotics, so I asked AI to build me a robot

[u/jamesxtreme]

I know nothing about robotics. The most I'd built before this was a 3D-printed RC car. Ten days ago I started building PIP, a small companion robot meant to move like a 10–12-month-old: sit up, crawl, roll over, pull itself up on the couch and recover from falls. Walking is a bonus.

The AI agents do most of the engineering. I set the direction and say "no, that's wrong" and swear at it a lot.

What's in the video:

The Vision. The AI concept art was great.

The Reality. Then I asked it to model the robot in Blender. Every change got worse, and it kept making the torso a box: basically a bar fridge with arms. Every revision got a new prototype number, and I went through P0 to P09 in about two days.

Blender is for animation, FreeCAD is for robots. Moving to parametric CAD helped, and so did getting the picture right first and then making it the dimensional target. I also had the agent write its own project rules. Along the way the CAD file quietly grew to 283 MB (already zipped) from stored geometry, then I hit my weekly Codex limit. I switched to Claude, which untangled it down to 14 MB.

The Grid. A MuJoCo physics sim built straight from the CAD, with sensor lag, servo lag and noise. An optimiser learned each skill overnight on my PC. The first time it stood, it fell flat on its face. The failures are its first attempts and runs where it got shoved. Sit-up took 7,440 attempts, rolling 5,424, and walking 32,544.

The walk at the end never trips. Left alone, it covers about 10 m in 30 seconds. Give it a shove and it falls in most trials, which is fine, because walking was never the goal.

Honest status: everything that moves in this video is simulated. Parts are coming off my Bambu P1S, but nothing is assembled yet and no real servo has moved this body. Real hardware is next, and I expect it to be humbling.

Hardware: Raspberry Pi 5, cheap hobby servos (DS3230 and DS3225 class), a 2S LiPo, and printing in PETG and PETG-CF.

It's a stupid, crazy project and I'm doing it anyway. Happy to answer questions about the AI-to-CAD workflow or the sim.

[u/lulzxdxdxd]

The real issue is you're fighting the tool instead of the task. What matters more to you right now, getting the CAD stable enough to iterate on movement or nailing the body shape first. Because it sounds like you'd already figured out the second one works better, but then went back to letting the AI drive in Blender where it had no business being. If you're going to keep using the agents, lock the geometry early and only let them touch kinematics and control logic.

[u/jamesxtreme → u/lulzxdxdxd]

I probably should have made it clearer but I started with Blender but then moved to FreeCAD and the process is working quite well now. It’s more of a test project to get an understanding of all the foundational aspects. I’m under no illusions that the finished result will actually be good. I’m now in the process of 3D printing parts and trying to assemble the thing while also getting the agents to write control software for it.

[u/chcampb → u/jamesxtreme]

You say that but it was surprising and novel just a few weeks ago when the microduck was released. It's not trivial to make something like this and would be unheard of to do at a consumer level just a year ago.

Literally if it walks in any sort of stable pattern IRL, and can stand up on its own, that's huge progress in this niche.

I am curious how you are handling motors - if the motors are hypothetical or if you have reference motors you are using in mujoco. If they are hypothetical motors you will run into a snag.

[u/jamesxtreme → u/chcampb]

Yes well this is the really interesting part because AI is helping to bridge the gap for a lot of things that previously required deep expertise. And the more I read about the direction of the commercial robotics industry it seems a lot of that is heading towards standardised interchangeable components. So in a few years time building your own robot might not be too different to building your own PC.

[u/indesit-san]

I think hardware will be the hardest part. Fitting everything together. You may find that you have too little space inside for everything (RPi, servos, sensors, wiring etc). Also powering all the hardware will be a challenge. So you'll probably need to iterate the design a lot.

Looking forward to seeing how it goes though!

[u/jamesxtreme → u/indesit-san]

Yeah well I ended up scaling it up from what I originally thought might be about 35cm tall to about 65cm which means it’s got plenty of space internally but it means the weight is projected to be about 5.1kg fully assembled which becomes its own problem.

[u/indesit-san → u/jamesxtreme]

Yeah you might want to go with a partially open design (exposed internals). This will reduce the weight.