If visual – or concrete – poetry helped illuminate the materiality of language, then Muji Rainbow focuses on the materiality of sound – or, to be exact, the materiality of a recording device. A contemporary interpretation of Duchamp’s Rotoreliefs (1935), Muji Rainbow is an audio CD designed specifically for the Muji Wall Mounted CD Player. Designed by Naoto Fukasawa in 1999, the CD player has established itself as a modern design classic. Yet what interests us is not its status as a design icon, but the simple fact that it reveals the surface of the CD that it plays. If you put Muji Rainbow in the machine and play it, a small rainbow will emerge along with a seven-minute silence – or the barely audible sound of the player’s own working.