It's stupid, but if it gets my kids to brush their teeth long enough... I took the chattering-teeth files and mashed them into one STL so it all prints in one piece (as a reminder of how grey your teeth will be if you don't brush). Then knocked out some more space inside and reduced the mesh with Meshlab to speed slicing. I glued some spacers inside the mouth to fit the microswitch from the blinky timer, but you could also make a new STL with your favorite program.