R/C robotics and battlebots.
The components that I used are hard to find now, but the good thing about this instructable is that it applies to all sorts of speed controllers, motors, and R/C equipment.
Step 1: Materials
1 R/C transmitter (Mine is a 5 channel, Spektrum DX5e)
1 R/C receiver (Mine is a Spektrum AR6115e, it has to be compatible with the transmitter)
1 Speed Controller***** (Mine is a Sabertooth RC-12 Dual)
2 GEARED Motors (I have no idea what mine are, I bought them from a friend)
2 Wheels for motors
1 X-Acto knife
1-2 Batteries (mine are 7.2v 1600mAh)
1 piece of foam board as big as your robot
10-20 Zip Ties
Wire (mine is stranded 18 awg copper wire)
***** The Speed Controller is what will kill you (figuratively) if you do not pick the right type. You want a dual channel 5-10 amp speed controller which will power your receiver.