Max Gibson Grok Mini Sub
Concept assembly guide derived from the staged build plan. Not a certified engineering drawing. Prices are estimates (Oct 2026); nothing here is a purchase. Every step and every BOM line links to the part. Downloads: step-by-step PDF · BOM PDF · original brochure PDF
Step-by-step build (one action per step)
Stage 1
- Cut and glue the PVC frame.Part M8: PVC pipe, fittings, pool noodle, dive weights ×1 · ~$25 · Buy: Amazon search
- Strap pool-noodle floats on top and dive weights below.Part M8: PVC pipe, fittings, pool noodle, dive weights ×1 · ~$25 · Buy: Amazon search
- Mount two horizontal thrusters on the rear.Part M1: cheeyoo 12 V brushed underwater thruster ×3 · $92.34 · Buy: Amazon B0D5JN1Z5R
- Mount one vertical thruster in the center.Part M1: cheeyoo 12 V brushed underwater thruster ×3 · $92.34 · Buy: Amazon B0D5JN1Z5R
- Solder thruster leads to three pairs of the 8-conductor cable.Part M4: 50 ft 18 AWG 8-conductor cable ×1 · ~$35 · Buy: Amazon search
- Seal every splice with marine heat shrink and liquid tape.Part M9: Marine heat shrink, liquid tape, silicone ×1 · ~$12 · Buy: Amazon search
- Tie the braided pull line to the frame (carries the load, not the wires).Part M5: Braided pull line 1/8 in ×1 · ~$8 · Buy: Amazon search
- Zip-tie the endoscope camera to the frame front.Part M2: USB endoscope camera, 15 m waterproof cable, LEDs ×1 · ~$30 · Buy: Amazon search
- Build the fused 12 V battery box topside.Part M6: 12 V 6 Ah LiFePO4 battery + 10 A fuse ×1 · ~$36 · Buy: Amazon search
- Mount three BTS7960 drivers inside the battery box.Part M3: BTS7960 H-bridge motor driver ×3 · ~$27 · Buy: Amazon search
- Feed the Pi 4 from the 12V-to-5V buck.Part M7: 12 V to 5 V 5 A buck for Pi ×1 · ~$10 · Buy: Amazon search
- Plug the camera into the Pi 4; confirm /dev/video0.Part M2: USB endoscope camera, 15 m waterproof cable, LEDs ×1 · ~$30 · Buy: Amazon search
- Test each thruster in a bucket before going in the pool.Part M1: cheeyoo 12 V brushed underwater thruster ×3 · $92.34 · Buy: Amazon B0D5JN1Z5R
Stage 2
- Assemble the Blue Robotics enclosure.Part M10: Blue Robotics 3-inch watertight enclosure, aluminum cap ×1 · ~$110 · Buy: Blue Robotics search
- Install the five WetLink penetrators in the end cap.Part M11: WetLink penetrators ×5 · ~$75 · Buy: Blue Robotics search
- Mount the Bar02 depth sensor in one penetrator.Part M12: Bar02 depth sensor ×1 · $80 · Buy: Blue Robotics search
- Mount the ESP32-S3 inside the enclosure.Part M13: ESP32-S3 board ×1 · ~$15 · Buy: Amazon search
- Wire the BNO085 to the ESP32 I2C.Part M14: BNO085 IMU ×1 · ~$25 · Buy: Amazon search
- Link ESP32 to topside over RS-485 on the spare tether pair.Part M15: RS-485 transceivers ×2 · ~$8 · Buy: Amazon search
- Add the 4th thruster as a second vertical.Part M16: 4th thruster (second vertical) ×1 · $30.78 · Buy: Amazon B0D5JN1Z5R
- Mount the two dive lights.Part M17: Self-contained dive lights ×2 · ~$40 · Buy: Amazon search
- Place the leak probe at the enclosure bottom.Part M19: DIY leak probe ×1 · ~$5 · Buy: Amazon search
- Vacuum-test the sealed enclosure with the plug and pump.Part M18: Vacuum plug + hand pump ×1 · ~$45 · Buy: Blue Robotics search
Bill of materials
| ID | Stage | Part | Qty | Price | Buy |
|---|---|---|---|---|---|
| M1 | Stage 1 | cheeyoo 12 V brushed underwater thruster | 3 | $92.34 | Amazon B0D5JN1Z5R |
| M2 | Stage 1 | USB endoscope camera, 15 m waterproof cable, LEDs | 1 | ~$30 | Amazon search |
| M3 | Stage 1 | BTS7960 H-bridge motor driver | 3 | ~$27 | Amazon search |
| M4 | Stage 1 | 50 ft 18 AWG 8-conductor cable | 1 | ~$35 | Amazon search |
| M5 | Stage 1 | Braided pull line 1/8 in | 1 | ~$8 | Amazon search |
| M6 | Stage 1 | 12 V 6 Ah LiFePO4 battery + 10 A fuse | 1 | ~$36 | Amazon search |
| M7 | Stage 1 | 12 V to 5 V 5 A buck for Pi | 1 | ~$10 | Amazon search |
| M8 | Stage 1 | PVC pipe, fittings, pool noodle, dive weights | 1 | ~$25 | Amazon search |
| M9 | Stage 1 | Marine heat shrink, liquid tape, silicone | 1 | ~$12 | Amazon search |
| M10 | Stage 2 | Blue Robotics 3-inch watertight enclosure, aluminum cap | 1 | ~$110 | Blue Robotics search |
| M11 | Stage 2 | WetLink penetrators | 5 | ~$75 | Blue Robotics search |
| M12 | Stage 2 | Bar02 depth sensor | 1 | $80 | Blue Robotics search |
| M13 | Stage 2 | ESP32-S3 board | 1 | ~$15 | Amazon search |
| M14 | Stage 2 | BNO085 IMU | 1 | ~$25 | Amazon search |
| M15 | Stage 2 | RS-485 transceivers | 2 | ~$8 | Amazon search |
| M16 | Stage 2 | 4th thruster (second vertical) | 1 | $30.78 | Amazon B0D5JN1Z5R |
| M17 | Stage 2 | Self-contained dive lights | 2 | ~$40 | Amazon search |
| M18 | Stage 2 | Vacuum plug + hand pump | 1 | ~$45 | Blue Robotics search |
| M19 | Stage 2 | DIY leak probe | 1 | ~$5 | Amazon search |
"Amazon search" links open a search for that exact part spec; no listing has been chosen and no affiliate tag is used. Nothing has been purchased.