I am in communication with someone in Japan (from Sankyo) about creating the music box movement from Elfen Lied! It will be almost exactly as in the show.
The only bad news is that to create this, it will cost around $670 initial fees to create the movement (engineering, manufacturing and composition fees), and then we could have it available for around $8-10. That would only be the mechanical portion, you would have to buy a separate box (that I know of thus far...)
So, the point is I'm trying to find people interested in such a project...right now it's in the beginning phase but I have started serious talks with the contact to figure out how to get the ball rolling.
If you're interested or have any more questions, post here, I'll try to keep it updated!!!