Oscillating Clock

Laura Evans and David Choi built an LED clock that displays a minute hand.
They built a printed circuit board which carries green and blue LEDs, and is spun by a motor.

They used a minimal number of communication wires to control the LEDs. The wires would get tangled if the motor spun all the way around, so they controlled it to oscillate 180 degrees.
The LEDs are turned on and off by a computer, according to the angle of the motor as determined by an encoder, to create the clock-like display.