Adding the other cubes creates more colored squares and a short musical sequence, with the pitch of each note determined by the cube's distance from the center. Once the cubes have settled into position, Imitations introduces a second voice, creating canons and other musical transformations from the original notes, until eventually the music dies away, waiting for another throw of the cubes. A camera beneath the playing surface captures images of the surface and transmits them to a computer, which compares what it sees with a reference frame of an empty surface in order to detect motion. The computer notes the position of any small objects thus detected, and projects a colored square onto the underside of the playing surface while playing the appropriate tone. The Copper Urchin is a copper sphere mounted atop a pole.
Flexible wires sprout from the surface.
Bending one of these wire antennas causes an LED to light up near the antenna's base and a sound to be played that can correspond to a musical note, bird calls, or whatever the artists have chosen. Each antenna of the Copper Urchin is embedded in a metal cylinder. When an antenna is bent, it makes contact with the cylinder and closes a circuit. Inside the Copper Urchin, 16-channel multiplexers pass the signal to a microcontroller, with one channel per antenna. The note is placed in a software queue and is then sent to an external MIDI player for conversion into the desired sound or tone.