How to build ToddlerBot
30-DoF humanoid robot · Expert
Build Stanford's ToddlerBot: a 30-DoF Dynamixel humanoid with printed parts, a pip-installable RL and diffusion-policy stack, about $5,700 in parts.
Research-grade: machining, motor drivers and control theory.
Our estimate, part-time
$5,727.94 (2XC) or $7,293.56 (2XM) for essentials per the project BOM, tools excluded
CC-BY-NC-SA-4.0 · non-commercial
What is ToddlerBot?
ToddlerBot is a small humanoid from Stanford (Haochen Shi, Weizhuo Wang, Shuran Song, Karen Liu) built to collect data and train policies at scale. It has 30 DoF on Dynamixel actuators and a 3D-printed body.
The software is the point. One pip-installable Python package covers low-level control, RL and diffusion-policy training, MuJoCo simulation and deployment on the real robot, and the team uses a digital twin for zero-shot sim-to-real.
Hardware files include Onshape CAD, printable meshes, assembly docs and KiCad PCB exports. The BOM sheet totals $5,727.94 for the 2XC version or $7,293.56 for the stronger 2XM.
ToddlerBot specifications
- DoF
- 30
- Actuators
- Dynamixel 2XC430, 2XL430, XC330, XC430, XM430
- Variants
- 2XC and 2XM
- Software
- Python, MuJoCo, RL + diffusion policies
- License
- CC BY-NC-SA 4.0 hardware, MIT code
Figures as published by the project. See Sources below.
Bill of materials
| Part | Qty | Notes |
|---|---|---|
| Dynamixel 2XC430-W250-T | 2 | |
| Dynamixel 2XL430-W250-T | 6 | |
| Dynamixel XC330-T288-T | 6 | |
| Dynamixel XC430-T240BB-T | 4 | |
| Dynamixel XM430-W210-T | 4 | |
| Onboard computer, cameras, PCBs and printed parts | — |
Where's the full bill of materials?
The full BOM, with exact quantities and vendors, lives in the project's own files. Prices change often, so treat $5,727 as a ballpark from the project. Start at the project repository.
Tools you'll need
- FDM printer
- Hex drivers
- Dynamixel Wizard
Step-by-step build overview
Electronics & wiring overview
Dynamixel chains connect to the onboard computer through the project's custom PCBs.
Software
A single Python package for control, MuJoCo sim, RL and diffusion policies, and deployment.
Tips from the bench
- ☕ Calibrate the digital twin carefully; sim-to-real depends on it.
ToddlerBot FAQ
How much does ToddlerBot cost?
About $5,728 for the 2XC build or $7,294 for 2XM, per the BOM.
Can I sell ToddlerBots?
No, the hardware is CC BY-NC-SA 4.0.
Sources
Written by Bots n' Beans from the project's own documentation. Check the sources for the latest revision before you buy parts.
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