Sono Plotter is a brand new instrument that uses a motorized vynil bow to play the three springs in the metal plate and also the plate itself.
The bowing speed can be controlled by varying the speed of the driving electromotor. The motor is controlled by an arduino. The arduino can in turn be controlled by the switches and knobs (not attached yet in the above picture). For a future version it is planned to directly control the Sono Plotter from a computer using the firmata protocol.