This is how I did one of mine.. Put a couple sheets of plywood together, roughly traced the outline of the rug, cut it out and stapled the rug to the plywood. Then, located a couple studs in the wall, determined the angle I wanted, notched the backside of the plywood and hung it.
I like the look of that! How did you secure the pieces of plywood together? did you use a stain on the plywood? This might get me permission to hang my rug in the living room, hehe
I used a couple of 1x4's and some screws though the plywood into the 1x4's. Think I also put some wood glue along the joint just to help. I originally did it as a way to hang it, but the way it turned out, it really "pops" off the wall and the plywood border does add some perceived size to the rug. It wasn't the biggest bear.

Yes, I did stain the plywood. Really didn't take much effort to make, but turned out pretty cool I think.