Anyone know of a circle that's fairly easy to work with?

I'm trying to do an electrical project that I am going to mount to a piece of wood with a hole in it. I want a circle that is about 6.5 inches in diameter and is empty on the inside. I don't mind doing some fabrication but I can't think of anything that has these specifics. If possible I would prefer something non metal as I will be mounting LED's to it. I think the outside of a speaker would work good because it has holes I can mount the unit to the board with but it's made out of metal. Any suggestions would be great.