Build a cd thrower, take the motor out of a portable cd player and stick it on the side of a piece of wood, wire it to some type of reciever switch for a remote control(I used an old keyless Entry box for my car). Wire it all to a 12v battery and install a linear actuator to sit right behind the cd motor.
On mine, when you push "lock" on the remote the cd starts spinning VERY fast. After it reaches high speed, press "unlock" and the linear actuator pushes the cd off of the motor, it hits the floor and takes off 100 mph! Fun project for school :wink: