The Swedish musician Martin Molin invented an acoustic instrument using 2,000 steel marbles and 3,000 wooden parts. The mechanism also contains a bass guitar, a vibraphone, drums and cymbals.
It looks less like an instrument and more like the physical design of a piece of software playing a loop. The pegs placed on the large wheel, which produce the sound at exactly the right moment, appear to have been arranged to follow one particular melody. To play a different melody you would have to reposition them, or mount a new wheel designed around a different tune.
Calling this an instrument is not quite right. It is a musical design. If someone handed it to you and said “play this piece”, there is a good chance you could not. It would need design work first. That is why it is not an instrument.
The build stages are shown here.
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