Open source Mini humanoids & bipeds
Zeroth-01 Bot (K-Scale)
An ultra-low-cost, hackable 3D-printed mini humanoid from the K-Scale Labs community: 16 Feetech bus servos, about US$347 in electronics, with end-to-end sim-to-real RL.
- Type
- Mini humanoid
- DoF
- 16
- Servos
- Feetech STS3250 × 16
- Controller
- Milk-V Duo S
- BOM cost
- ≈ US$347 (electronics)
- Status
- K-Scale closed in Nov 2025; project open-sourced
- Open hardware and open code
- Full bill of materials with supplier links
- Direct links to the original CAD, code and papers
01 — Project details
Overview, BOM and resources
Overview
Zeroth-01 (formerly MicroStompy) is the K-Scale Labs community’s entry-level humanoid — “BOM starts at $350”. Printed parts plus 16 bus servos, with a camera, microphone and round display for vision and voice.
K-Scale Labs ceased operations in November 2025 and open-sourced all K-Bot and Zeroth Bot hardware and software (hardware CERN-OHL-S-2.0, software MIT). The old docs site is offline; GitHub is now the source of truth.
Key specifications
| Servos | 16 × Feetech STS3250 50 kg bus servos (STS3215 is too slow, no longer recommended) |
|---|---|
| Controller | Milk-V Duo S + Waveshare bus-servo adapter |
| Sensors | Adafruit 9-DoF IMU, Milk-V camera, microphone, 3 W speaker, RP2040 round LCD |
| Software | kos-zbot (robot OS), ksim-gym-zbot (RL training) |
Bill of materials
Electronics total ≈ US$347 (servos at historical price; current price varies by seller). Fasteners and prints are unpriced in the official BOM.
| Part | Model / spec | Qty | Unit | Subtotal | Supplier |
|---|---|---|---|---|---|
| Electronics | |||||
| STS3250 50KG Serial Bus Servo | 16 | $13.89 | $222.24 | aliexpress.us ↗ | |
| Milk-V | 1 | $10.00 | $10.00 | milkv.io ↗ | |
| Waveshare Bus Servo Adapter | 1 | $7.00 | $7.00 | waveshare.com ↗ | |
| RP2040 MCU Board | 1 | $16.00 | $16.00 | waveshare.com ↗ | |
| 9-DOF IMU | 1 | $29.95 | $29.95 | adafruit.com ↗ | |
| Milk-V CAM-GC2083 | 1 | $4.00 | $4.00 | arace.tech ↗ | |
| RC Lipos | 1 | $33.00 | $33.00 | amazon.com ↗ | |
| 12V to 5V, 3 amp capacity (may need connectors) | 1 | $3.00 | $3.00 | digikey.com ↗ | |
| Electret Microphone | 1 | $6.00 | $6.00 | amazon.com ↗ | |
| 3 Watt Speaker | 1 | $8.00 | $8.00 | amazon.com ↗ | |
| LM386 Mono Audio Amplifier | 1 | $8.00 | $8.00 | amazon.com ↗ | |
| Total | $347.19 | ||||
Optional items, tools and reference items (not counted)
| Part | Model / spec | Qty | Unit | Subtotal | Supplier |
|---|---|---|---|---|---|
| Fasteners | |||||
| Button Head Cap Screw | M3 x 10 mm | 14 | |||
| Button Head Cap Screw | M3 x 4.5 mm | 129 | |||
| Button Head Cap Screw | M2 x 5 mm | 80 | |||
| Socket Head Cap Screw | M2 x 5 mm | 12 | |||
| Heat-Set Insert | M3 | 13 | |||
| Heat-Set Insert | M2 | 14 | |||
| M3x12 screw + nut | M3 x 12 | 4 | |||
| Structural | |||||
| 3D-printed parts (see STL pack) | see print pack | ||||
| Total | $347.19 | ||||
3D printing & fabrication
- Official settings (Bambu): 0.16 mm layers, 5 walls, tree supports; filament is not specified — PLA or PETG both work.
- The official print pack has 22 STLs and a Bambu .3mf plate (hands, elbows, shoulders, head, neck, torso, hips, knees, ankles, feet).
CAD, code & papers
Get the large files — CAD, STL, STEP and code — straight from the original project:
- GitHub zeroth-bot ↗github.com
- Releases (URDF, CAD) ↗github.com
- Docs source (incl. STL) ↗github.com
- Custom PCBs ↗github.com
- Robot software kos-zbot ↗github.com
- RL training ksim-gym-zbot ↗github.com
- CAD (Onshape) ↗cad.onshape.com
License
The zeroth-bot repository currently carries only an MIT license (the README says MIT too). K-Scale’s November 2025 shutdown announcement says hardware is released under CERN-OHL-S-2.0 and software under MIT, but no CERN-OHL-S file has been added to the repository yet — follow the repository files and keep attribution.
Image credits
- Image 1: Zeroth Robotics / K-Scale Labs · repo MIT — source ↗
- Image 2: Zeroth Robotics / K-Scale Labs · repo MIT — source ↗
- Image 3: Zeroth Robotics / K-Scale Labs · repo MIT — source ↗
- Image 4: Zeroth Robotics / K-Scale Labs · repo MIT — source ↗
- Image 5: Zeroth Robotics / K-Scale Labs · repo MIT — source ↗
- Image 6: Zeroth Robotics / K-Scale Labs · repo MIT — source ↗
Source: Images and data: Zeroth Robotics / K-Scale Labs community (GitHub zeroth-robotics, kscalelabs). Repository code MIT; on shutting down K-Scale announced the hardware under CERN-OHL-S-2.0. This site is not affiliated with the original project.
Get the parts
Where to get the parts
Every line in the BOM links to the supplier the original team used. Need help sourcing parts or 3D-printing the structure? Tell us which robot you are building.
02 — Related robots
