PhotonBoy
Flashlight Enthusiast
http://www.tlb.org/scooter.html
"Balancing lateral scooters, like the Segway™ are often thought to be technological miracles, but it is not actually very hard to build a balancing scooter. I built the one described here for my own amusement, and to help me understand the control theory behind it. (I work a lot on balance, mostly for walking humanoid robots.)... I put this scooter together in a week using off the shelf parts. Altogether it cost about $2000...."
"Balancing lateral scooters, like the Segway™ are often thought to be technological miracles, but it is not actually very hard to build a balancing scooter. I built the one described here for my own amusement, and to help me understand the control theory behind it. (I work a lot on balance, mostly for walking humanoid robots.)... I put this scooter together in a week using off the shelf parts. Altogether it cost about $2000...."