I just love Owen Schuh’s Pythagorean Nightmare, an ornate painting machine that mixes the mechanical and electronic.
Built from scrap wood and metal, a broken ladder, a hang-glider pole, numerous bicycle parts, a door, used chemistry equipment, solenoid valves, light sensors, an arduino micro-controller, window counterweights, and a non-alcoholic beer.
The machine is driven by a mechanism similar to that found in an old clock. The weight (the blue bottle on the yellow rope) is wound up and its descent powers the movement. The speed of the descent, and thus the movement of the machine, is kept regular by use of a pendulum and escapement. The wheel that the painting / light sensing mechanism is attached to both rotates and revolves around a smaller fixed wheel (at the end of the pole) in a “spirograph” type pattern.
Light sensors are activated by passing over the machines own shadow. Their signal is then processed by the micro-controller and run through a simple algorithm, which activates the valves, releasing paint. The resulting image feeds back into the light sensors creating a perpetually evolving work of art.