I had a lot of fun making this very simple beetleblocks project, which makes a simple set of pan pipes (just a set of capped tubes of different lengths), and printing it out:
By blowing over it I can play a set of different pitches. I think it needs to be printed a bit bigger to get really good sounds out of it. And there is some work to do on the math for computing the lengths of the pipes, so that the notes form a musical scale. I'd love to see some remixes of this project if anybody is interested!