Rasper’s sound-generating mechanism is based on surface friction between a sharp piece of spring steel and a plastic disk rotated by a DC motor, while the contact between the two is made using a linear actuator. In Rippler, the actuation noise of the linear actuator is amplified and transduced using a thin sheet of steel, whereas in Mutor, the sonic output is the noise of a DC motor, modulated in terms of timbre and amplitude.
The instruments are driven using a custom-built driver board that has been designed as an Arduino Mega shield. The Arduino board itself is converted into a MIDI device using the HIDUINO protocol, and the communication is done using MIDI messages from software. The circuit was designed using Altium Designer. All instruments were designed in SolidWorks and the enclosures were laser-cut from sheets of clear acrylic.