Handcuffs

This is a easily printable model that is well functioning and lots of fun. If your key breaks or gets lost you can make another or, if in need of a faster solution, use something like a bent paper clip to push the lever inside of the cuffs. There are now a new files for smaller printers. 1.75 filament fits through the holes like a pin. You may need to glue in the pin but it should friction fit.