SO-101 Bill of Materials and Real Cost in 2026: Assembled Kit vs Servo Set vs Self-Sourced
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A complete SO-101 leader–follower pair costs between about $330 and $550 depending on how much of it you source and print yourself. Below is the full bill of materials with 2026 prices, followed by the three ways people actually buy it.
Bill of materials for one leader + one follower
| Component | Qty | Typical price |
|---|---|---|
| Feetech STS3215, 6 × 12 V + 6 × 7.4 V (three ratios) | 12 | $249.99 as a set |
| Metal main + rear horn sets | 12 | $32.99 per 6 |
| USB servo adapter (Waveshare or BusLinker) | 2 | $14.99 – $16.99 each |
| 3-pin servo cables, mixed lengths | 24 | $17.99 per 12 |
| 12 V 5 A adapter + 7.4 V 3 A adapter | 2 | $15–20 each (7.4 V here) |
| 2-inch G-clamps | 4 | $24.99 |
| PLA, ~1 kg | 1 | $15–20 |
| Wrist camera + overhead camera | 2 | $30–40 each |
| Overhead camera desk arm | 1 | $39.99 |
| Training objects | 1 set | $24.99 |
Three ways to buy it
| Route | What you get | Approx. total | Best for |
|---|---|---|---|
| Assembled SO-ARM101 kit (Starter / Standard / Advanced) | Both arms built and calibrated, boards, adapters, clamps; cameras on Standard and Advanced | $450–550 | Labs and anyone without a printer; fastest to first dataset (about an hour) |
| Servo set + Builder's Pack + your printer | 12 servos, all hardware and cables, free STL files; you print about 1 kg of PLA | $380–400 plus filament | Makers with a printer who want colour choice, STS3250 options and spares knowledge |
| Fully self-sourced | Buy every line above separately | $330–420 | Bulk classroom builds; more orders and more things to get wrong |
Hidden costs people forget
- A second 12 V adapter if you run the follower hard; one 5 A adapter is the minimum, not the comfort level.
- Spare cables and one spare STS3215: a single dropped servo stops a recording session.
- Shipping weight: an assembled pair is 4–6 kg; parts and servos ship at under 2 kg.
FAQ
Is self-sourcing really cheaper than a kit?
For one pair, the saving is $60–120 and you gain colour choice and STS3250 options. For a classroom of five pairs the saving is meaningful. For one arm with no printer, buy the Starter kit.
How long does printing take?
About 30–36 hours of print time for a leader + follower pair on a 0.4 mm nozzle at 0.2 mm layers, roughly 900 g–1.1 kg of PLA.
Do I need the cameras?
Not for teleoperation. You need at least one camera to record datasets, and two views for the standard ACT tutorial.