I like building modded instruments for concerts! In my family we currently have, among lots of other things, a balalaika that opens into a music box (incl. ballet dancer!), another balalaika that doubles as a flute (built into the neck) and a racing-mandolin with a RC car inside. It's very popular when it races onto the stage just in time for that solo! ;-)
I obviously need to learn more about RC helicopters now. Ukuleles aren't very heavy but I'll need quite a bit of lift to carry the extra weight... Do you have any tips, thoughts, experience on what model I should buy to tinker with?