Pushing a button produces a tone/chord and subsequenly a piece of music. Let's use the sound of a piano as an example. So upon pressing the button('s) (say not more than two) the tones and/or chords of a piece of music are reproduced one by one and the volume of each individual note/chord is determined by the intensity of each press. So the piece or song has been written and recorded but the person pushing the button(s) determines how it is performed: the volume of each note/chord and the time intervals between them.
Ever heard somebody play the piano, wheter classical music, blues, something popular, or something else, and thought you would like to hear it (just a little) differently? Take Scott Jopplin's 'The Entertainer' for example, imagine you produce and structure it just the way your musical imagination would like it.
Any reader seeing the same potential?
Reward: That somebody gets the idea.