Petros Vrellis made these 2 pendulums which can draw. He used openFrameworks and some electronics to let the pendulums drop ink at the right time on the right spot. The first one is called “Irrational pendulum” and draws a square. The whole process takes around 6 minutes. The video shows this at a faster speed.
The second one is called “A drawing pendulum”. The pendulum need 15 minutes to draw this face.
found at make blog