Functional "sweet potato" style ocarina. English 5-hole fingering. Plays A4 - B5 -- might be some variation/error depending on your printer.
Was surprised not to see any examples of working printable traditional-form ocarinas up here, so I made this up. Let me know what you think, or recommend any changes. If anyone's interested, I'll make some alternate versions (fingering patterns, shapes, keys).
edit-- whoa, wasn't expecting this much attention. If you like this thing, tips are appreciated. I really need to buy a "real" ocarina to use as a model to have an easier time making different ocarina styles.
The ocarina is split into two halves for reliable printing without support material. Don't rescale it (original size should be ~4.25" long) or it won't play as expected. Print the halves with the flat side down. Use the thinnest layer height you can manage to help prevent problems with the voicing (I used .1mm / MakerWare 'High' preset).
After printing, glue the halves together. Make sure there are no air leaks along the edges.
If you have a printer with dissolvable support material, you should be able to recombine the halves and print it as a single piece, but make sure the airway doesn't get clogged with support.