I have successfully produced 4 prototype electric skateboard controllers. Here are the specs:
- Modes: Car/Boat and Electric Skateboard
- Sensitivity: 1000 degrees
- Input Voltage: 4.5~6.5 VDC
- Max Voltage Measurement: 55 volts
- Failsafe: Slowly turns off the motor
- Dimensions: 50.0 x 38 x 12mm
Edit (September 20, 2015):
These controllers are almost ready to ship. All that’s left is to waterproof each circuit using epoxy resin, and ensure compatibility across all Android devices.
Edit (August 1, 2016):
Due to limited demand, I have not gone through with manufacturing these controllers. If you would like a prototype controller for $30USD, please contact me at [removed]. I have also open-sourced the controller and plans here.