I had a frameshop (in my case the one at the Hobby Lobby where I work) make a matboard pattern. The one I use now is 11 outside edge diameter and 7.5 inside edge diameter. If I make a draw-string/ribbon, this works out great. I am planning to make another with a 7.25 inside circle. I may try a 11.5 inch outside too. I paid $4.80 (the same as for an 11x11 picture matt). Prices may now be different, as the pricing system has changed.

The advantage is quick measuring and cutting of the pieces.

Tip-> to make a fitted hat, measure head with a soft tape measure and divide by 3.15 to convert to a diameter circle.