SO-101 Open-Source Robotic Arm

What it is:
The SO-101 is a standardized open-source robotic arm developed by RobotStudio in collaboration with the Hugging Face LeRobot team. It is the successor to the SO-100, with improved cable routing and assembly that does not require disassembling the gears. It is designed specifically for teleoperation and imitation learning with the open-source LeRobot library.

Hardware list and approximate cost:
The leader and follower arms both use STS3215 servos: six for the follower arm and six for the leader arm, with slightly different models. They are paired with a Waveshare motor-control board and 3D-printed structural parts. According to the official BOM, both arms together—one leader and one follower—cost approximately $229.88. A follower arm alone costs about $121.94. Neither figure includes 3D printing, taxes, or shipping.

Overview of replication steps:
1. Follow the Sourcing Parts list to purchase the servos and control board in the US, Europe, China, or Japan
2. 3D-print the leader and follower arm components in PLA+ using a 0.4 mm nozzle and 0.2 mm layer height, or use the officially recommended print settings
3. Before printing, use the Gauge file to verify the printer’s accuracy
4. Assemble the leader and follower arms according to the official Assembly Guide
5. Configure the servos using Feetech software or directly through the LeRobot library
6. Follow the official LeRobot tutorial to set up teleoperation and collect demonstration data

Getting-started advice:
STS3215 servos come in 7.4 V and 12 V versions, so do not mix them up. The 12 V version provides more torque but requires a 12 V power supply. It is recommended only when the follower arm needs higher torque.