A five-finger, tendon-driven robot hand from Chestnut Robotics (formerly TetherIA) with 7 actuated DoF moving 16 joints, weighing about 389 g. Seven Feetech serial servos in the palm wind cables on spools, and an ESP32-S3 board runs the firmware. A Python SDK, ROS 2 package and MuJoCo model are included.
At a glance
| Parts cost | $320 parts list · Sum of the prices in the project's parts list. The complete kit sells for $314 source ↗ |
|---|---|
| Difficulty | 3/5 Intermediate · Tendon routing, spring fitting and silicone pad casting, but the design is modular and a PDF guide covers each finger. |
| Build time | Not stated |
| Tools needed | 3D printer (Bambu X1C settings given, PLA), silicone casting for finger pads (Ecoflex 00-30, printed molds), small Torx drivers |
| Motors | 7 Feetech HLS3606M serial servos with tendon spools |
| Controller | Seeed XIAO ESP32-S3 + TTLinker serial board (custom PCB optional) |
| Sensors | Servo feedback only |
| Published | ✓ Parts list✓ CAD/STL✓ Assembly guide✓ Wiring✓ Software✗ Video GitHub monorepo + docs.tetheria.ai site with assembly PDF + CSV parts list + Onshape + KiCad PCB |
| Activity | Last update 2026-09-15 · 976 GitHub stars · Discord, GitHub Discussions; 154 forks |
| Kits | Complete kit sold by Chestnut Robotics ($314 per README) |
Licenses
The design license is non-commercial. Building one for personal, educational or research use is allowed, but selling builds, parts or kits is not.
| Design files | CC BY-NC-SA 4.0 source ↗ |
|---|---|
| Code | Apache-2.0 (firmware and SDK) source ↗ |
| Documentation | CC BY-NC-SA 4.0 source ↗ |
Builder notes
Practical points from the project's issue tracker, forum and docs, each linked to its source.
- All silicone pads in the parts list should be Ecoflex 00-30. The rows that list 00-31 to 00-33 are a typo. source ↗
- Vectran tendon creeps less and lasts longer than the Kevlar line in the parts list, though the difference is small. 0.8 mm cable is recommended. source ↗
- Early assembly docs used different servo IDs than the firmware. The convention is now IDs 0-6, and the guide was updated to match. source ↗
- The design license forbids printing parts or kits for sale, even though bought hands may be built into commercial products. source ↗
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