A gravity-powered instrument.
Draw a piece of glass. Every drop that strikes it plays a note. Higher glass sings higher. A slope sends drops sideways, toward whatever you put below.
Reshape the weather. Drag the ends of a rail, or use Move to shift the whole thing. Drag a cloud sideways; tap it to stop its rain.
Keep a particular shower. “Bottle this rain” downloads a playable copy of your instrument. It works offline, just like this one.