Egg timer using nothing but its mechanical internal circuit to function as a timer for an electrical circuit a.k.a. no timer chip.
1x switch (on/off)
1x piezzo buzzer
1x blue LED (sanded)
1x battery holder
2x AA 1.5v Batteries (standard ones)
dremel with drill bit
Edit: I've been searching for a similar timer so i could recreate the steps but I've had no such luck. I'm sorry guys :( The main thing here is to connect an LED lead (just the lead snipped from an LED) to the base and another to the moving gear of the watch. When they touch each other they form a connection. Use hot glue to avoid short circuits! I used the lead from an LED because it was the only strip of metal that was both hard and bendy and wouldn't lose shape on its own.