SwitchKart

 

I made this in a hack-a-thon style event at the beginning of my senior capstone project at BYU.  The car was tasked with crossing the floor, knocking over bottles, then returning back the user.  This car would take off under battery power, then at upon crashing in to bottles, would expend a length of string dragged behind it that would grow taut and pull a switch to reverse the car an accelerate back.  The car successfully completed the challenge.