5-DOF arm · 2025
SO-101
The $100 arm that changed who gets to do robot learning. A five-bar printed arm driven by six STS3215 serial servos, trained by teleoperation — you move it, it copies you, then it repeats. This is the hardware that made imitation learning a hobby.
$110
The Robot Studio / Hugging Face
5 (+ gripper) DOF
Open source
Why it matters
Learn the whole loop — CAD, assembly, calibration, teleop data collection, policy training — for the price of one Dynamixel.
Where it falls short
No force sensing, no absolute reliability, and repeatability of a few mm rules out tight assembly work.
Read this if you plan to copy itThe parts below are the same classes of component at this platform scale — they are not the exact vendor parts. Use them to understand the architecture and to price a home-built equivalent.
What it is made of
| Subsystem | Comparable part | Price | Primary spec |
|---|---|---|---|
| Actuators | Feetech STS3215 | $17 | 30 kg·cm (2.94 N·m) @ 7.4 V |
| Compute | RP2040 / Pico 2 | $4 | 2× Cortex-M0+ @ 133 MHz (Pico 2: RISC-V/M33 option) |
| Structure | PA-CF printed structural parts | $40 | ~70 – 100 MPa (depends on print) |
Software you would touch
LeRobot · Python · Feetech SDK