Starting the next generation Fitbit Cheat-O-Matic, but changing the name, switching to proper high-end bearings, and make a sturdier base and cam follower mechanism. Should be slick if everything fits nicely and plays nicely.
I'm building a bright LED reading light that will be powered by a "9V" wall wart power supply and will use a flexible stem to position the light to not disturb my wife while I read and she sleeps.
