You guys should check out DA Graphite
www.dagraphite.com
I've been ordering from them since the '80s. Very good quality quasi-isotropic flat sheets. I'm not sure if he can do angles or not. Well right angles at least. He does have forms for 30 and 20 degree kick ups. I'm sure he could form it off some aluminum angle, but that stuff is never perfectly 90.
He also does custom fab from a sample piece. He supplies some other aftermarket companies with their stuff.