Please, this is something I have thought of a long time, but don't have unlimited supplies to keep doing it wrong. I want to make one of these for my nephew, he's interested in science!
There is a Physics Toy, called "Swinging Sticks", used in the movie "Iron Man 2", on Pepper Pott's desk. How can I calculate the 2 balance points for the "sticks" in this toy, to make it keep spinning a long time? - Here is a great Youtube video of the toy: