Question For Custom Guitar Makers

I've got a good friend who is a respected guitar craftsman who mainly works for a lot of country/western musicians here in TX. I'm basically asking this for him because he may be doing some work for me.

What is the story on patented guitar body designs? He has a great one he built but doesn't want the design stolen. I know in the art world (I'm a painter) that as soon as you stick a copyright symbol with your name on anything you create it becomes legally your design. How does it work for guitars?

Thanks.....