This is the prototype of a clock I'm building with the kids (4 and 6). I'm letting them drive the project, which has led to some interesting design choices.
If you look closely, you'll see that the numbers are out of order. The black hand points to the hours and the white hand to the minutes. Every five minutes, the hands reposition themselves to the correct time.
Behind the scenes, I'm using an Arduino to drive two micro servos. I also plan to add a relay so I can completely power down the servos between adjustments. This will cut down on power consumption and eliminate any buzzing from the servos.