I got my first diatonic music box a while back, and then started searching for a chromatic one. I finally found one here: http://www.deanorgans.co.uk/order_musicalmovements_mbm30hp.htm
The video above is the Great Fairy Fountain theme, adapted by me for the music box.
I'm working on modifying the gear system a bit. The problem is that the holes on the same line (same note) have to be a certain distance apart in order to play the same note twice in succession. The solution is to scale the piece so that all the holes are farther apart. The problem is that then you have to turn the music box handle really fast to make the same tempo as before. I'm going to pick some gears out of my collection (yes I have a gear collection) and try to fix this problem.
The next music box related project is to get large sheets of cardstock and use a laser cutter to cut them out and also punch them with tunes I've adapted for music box. I also want to write some code to create either an easy system for writing music for the box or for adapting pieces from the tool I already use, Noteflight.
Finally I'll want to build a permanent 'box' for the music box--something nice, maybe cherry wood. I'll need to think carefully about the design in terms of resonance, but also handle placement, weight, ease of use, etc. The design of any particular project is always way more complicated than I expect it to be.