Gone!for music-box ‘piano’ and helium balloons (2007)
Attach a long ribbon to the wind-up ring on the music-box piano so that it can be retrieved from the audience afterwards. Attach about 20 helium balloons to the top of the music-box. Finally, tether it to the inside of whatever concert grand you are playing, to a strut for example. If possible, this should be done in advance, and the little piano should not be visible to the audience until it is released.
Before you cut the tether and free the piano to float off into the hall, wind it up and start it playing, but I suggest you conceal its sound with some other sound as you release it—for example, a glissando across the higher strings, then with luck the audience will quiet down until they can hear it.