blinks until the right brushing interval is done
It's stupid, but if it gets my kids to brush their teeth long enough...
I took the chattering-tee...th 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.
3d model print parameters
Print in PLA so you can fold the upper jaw over the lower jaw. Add spacers for your blinky timer if needed. Use poster putty or other removable glue t...o hold the timer in place so you can replace the battery when the time comes.