Procedurally-generated panpipes for 3D printing. They really whistle, but they aren't particularly accurately tuned. OpenSCAD file included.
It'll theoretically play a chromatic scale (12 notes to the octave) but it's too squeaky to know for sure!
It took about 20 minutes to slice in skeinforge, and almost 4 hours to print on a Thing-O-Matic with 1.8mm filament.