How fast does it need to turn? Maybe you could find one of those lights with a three-color disc, from the '60s and adapt it.

A friend used one of those when his band dissolved and he went solo- called it his 'million dollar light show'.

If you check nearby, you may find a group called Makerspace or something similar. They do all kinds of interesting and inventive things.

You might find something here-

[Link: amazon.com]