ElectroHarmonograph - i3Detroit

A Harmonograph is 19th-century mechanical device which draws geometric patterns based on the motion of pendulums. (For a real example, see Marie-therese's Maker Faire project - A 3-pendulum Harmonograph. Also, search youtube for videos like this one) By adjusting the physical parameters of the device, and initial conditions of the pendulums, you can vary the patterns it can make.