In 5th grade i made a little device using parts from one of those musical greeting cards, a washer(as a contact) and some thermocol (as a float) to act as a warning device when a bucket of water was almost about to overflow (no shower at our house in those days). It was for some school "crazy inventions" competition, but the judges never believed that i made it myself,

and instead the guy who taped two markers together to make a cool writing device won the prize
cya
R
ps - got a huge burn from shaking off the solder from the hot iron onto my leg!