3) Easy build Arduino twin wheel skateboard

The plan this time around is to see how simple and low cost I can make this tech, so much less daunting challenge, but still capable of carrying an adult. Using KISS (keep it simple stupid) design ethos!
- Arduino microcontroller powered by its own 9V battery
- Electric scooter motors from ebay
- Commercial motor controller (no point skimping on this)
- Cheapest possible Sparkfun IMU module
- Electric scooter wheels with axles and sprockets already sorted out for you.
- Wheels small enough to go underneath deck rather than sticking out of the sides.
- NO welding required just bolts together.
- Fit your own skateboard deck or robot body.
- Use whatever batteries you have or can afford.
- Simple hand controller with motor cutout, steer-left, steer-right and balance-point-fine-tune switches.
- If space the wheels further apart can use to make a small segway style machine.
- Has second gyro in IMU to resist sudden spins if one wheel hits small obstruction (easier, cheaper, more abuse resistant than wheel encoders).
- Approx £300 GBP in parts but £ is weak at present, would be much less in the US.
This would be a great school technology project so the idea is that it could be built by a teenager interested in electronics, with some practical help.

YouTube Video

Build Instructions here on Instructables.com :  
This is made from exact same components as in my instructable but all bolted to a large skateboard deck.
This must be braced underneath or along sides as it bends slightly when you stand on it - this makes the chains slacken off otherwise.
Top view of new version on this theme, built March 2011
Side view of March 2011 version.
CODE (Arduino): The code is attached to this page of my "Instructables" site on how to build this, and the subsequent 5 pages.
The code is as a text file which you need to fully copy then paste into a blank new Arduino sketch. Note: The code was written using Arduino V22 not V1.0 which will need one or two syntax changes to code to make it work. See the Q and A section below this Arduino-Segway(TM) instructable that uses variation of this same code for some pointers on how to do this:
 How to tear apart a Wii Nunchuck to use the potentiometers inside it and the end buttons using a multicore cable back to 2 analog inputs (potentiometers) on the Arduino board:
 Special 3 lobed screwdriver from ebay.
Fiddly soldering. Note the 5V and GND only need to be connected to the ends of one of the 2 potentiometers controlled by the thumb joystick
- they are joined to the other potentiometer on the PCB.
Note: The pots in a real Nintendo Wii Nunchuck have resistance of about 16K
The pots on a fake one (externally identical but you can tell by the price) have resistance of about 3K Ohms.
I would suggest getting the proper Nunchuck.