The Mendocino Motor is a great project in which you make a solar powered, magnetically levitating motor. We use a 1 inch square balsa block to serve as the rotor, cut the corners off with a 1/4 inch router bit. The motor is wrapped with 32 guage magnet wire. the solar panels are 3/4 inch by 1 3/4 inch cells with tabs. When it is running well, it goes pretty fast.
Click on the video to see it run.
Mendo Motor Process - link
Mendocino motor measurements - Link
photos - link