The SO-101 Builder's Pack is a hardware bundle for people building a LeRobot SO-ARM100 / SO-ARM101 arm from their own STS3215 servos and 3D-printed parts: the USB servo adapter, metal horns, servo cables and desk clamps that boxed kits include but nobody sells separately, together with a free download of ArmDojo's SO-101 print files.Everything around the servos that an SO-101 build needs and that nobody sells as one bag: the USB servo adapter, twelve metal horns, the right cables in the right lengths and the clamps, plus a free download of our 3D-print files. Pair it with a 12-servo STS3215 set and a roll of PLA and you have a complete leader–follower rig for a fraction of a boxed kit. Power supplies are not included (they are hard to ship internationally); any 12 V 5 A or 7.4 V 3 A adapter with a 5.5 × 2.1 mm plug works.What can you use it for? Completing a Seeed or Feetech 12-servo set into a working leader–follower pair Building a second follower arm for bimanual setups Classroom builds where students print the parts themselves Replacing the miscellaneous hardware after moving a kit between labs Who is it for?Makers and labs who already have (or are buying) STS3215 servos and a 3D printer, and want the rest of the bill of materials in one order.Compatibility Arms: SO-ARM100, SO-ARM101 (LeRobot SO-101), leader and follower Servos: 6 × Feetech STS3215 per arm (12 V for follower, 7.4 V mix for leader), sold separately as the SO-ARM101 12-servo set Software: Hugging Face LeRobot so101 configs; the Waveshare adapter appears as a serial port Printing: PLA or PETG, about 1 kg per pair; files download after purchase Getting started: from unboxing to your first LeRobot dataset Print the parts from the download link in your order email (leader and follower STLs, camera brackets). Set the servo IDs 1–6 with the Waveshare adapter and the Feetech tool before assembly. Fit the metal main + rear horns to each servo and assemble the joints following the SO-101 guide. Wire the chain with the 15 / 20 / 40 cm cables, base servo to the adapter. Clamp the base to the desk with two G-clamps, connect a 12 V (follower) or 7.4 V (leader) supply and USB, and run LeRobot calibration. Specifications For SO-ARM100 / SO-ARM101 (LeRobot SO-101) arms built from your own or our free 3D-printed parts and 6 Feetech STS3215 servos per arm Per arm 1 × Waveshare Bus Servo Adapter (A), 6 × STS3215 metal main + rear horn sets with screws, 12 × 3-pin servo cables (4 × 15, 4 × 20, 4 × 40 cm), 2 × 2-inch G-clamps 3D files Free download of ArmDojo's SO-101 print files (STL, leader and follower) with every order; link is in the order confirmation Not included STS3215 servos (sold separately: SO-ARM101 12-servo set), printed parts, cameras Pair pack Two of everything above: two adapters, 12 horn sets, 24 cables, four clamps Power supply Not included. Follower (12 V STS3215-C018): 12 V ≥ 5 A; leader (7.4 V servos): 7.4 V ≥ 3 A; both with a 5.5 × 2.1 mm centre-positive plug Country of origin China; packed and shipped from Singapore (kit assembled in Singapore from Chinese components) What's in the box One arm (follower or leader): 1 × Waveshare Bus Servo Adapter (A), 6 × STS3215 metal main + rear horn sets with screws, 12 × 3-pin cables (4 × 15, 4 × 20, 4 × 40 cm), 2 × 2-inch G-clamps, download card for the 3D-print files Leader + follower pair: 2 × Waveshare adapters, 12 × horn sets, 24 × cables, 4 × G-clamps, download card Shipping and returnsShips from our warehouse in Singapore with tracking. Parts and accessories are charged by parcel weight, the same rates everywhere: $11.99 up to 250 g, $19.99 to 500 g, $34.99 to 1 kg and $59.99 to 2 kg. Orders over $100 that stay under 500 g ship free. Standard tracked runs 5–18 business days; DHL Express (3–5 business days) is offered at checkout if you need it sooner. Within Singapore: $6, or free over $110. Assembled robot-arm kits over 2 kg are built and calibrated to order in Singapore (dispatch in 7–10 business days) and ship worldwide at carrier cost: SingPost Speedpost Priority from $124.99 (10–14 business days) or DHL Express from $229.99 (3–5 business days), shown at checkout. 7-day returns; defective items are replaced or refunded with shipping covered. Import duties, where charged by your country, are paid by the recipient.One parcel, one shipping charge: small parts travel together, so the postage on a single 70 g servo is the same as on six of them. A 500 g parcel holds roughly six servos plus horns and cables — which is also about where an order passes $100 and ships free. If you are buying one small item, it is usually worth checking what else you will need for the same build.Frequently asked questionsWhat is not included?The servos, the printed plastic parts and the power supplies. Add the SO-ARM101 12-servo set from this store, print the parts from our free files, and you have a complete pair. Cameras are optional and sold separately.Which power supply do I need?None is included, because mains adapters are hard to ship internationally. The follower (12 V STS3215-C018) needs 12 V at 5 A or more; the leader (7.4 V servos) needs 7.4 V at 3 A or more. Both use a 5.5 × 2.1 mm centre-positive barrel plug — label them, since the plugs are identical.Are the 3D files really free?Yes. Every Builder's Pack order includes a download link to ArmDojo's SO-101 print files, licensed for personal and educational use.Is this cheaper than a boxed DIY kit?Servo set plus Builder's Pack comes to roughly the price of the Hiwonder DIY kit while letting you print the parts in any colour and swap in STS3250 shoulders.
