Thank you everyone! I think the safest route sounds to be to make my own template with a compass. We have a very deep mattress so this is going to need to be pretty big to cover it. In fact, that's one reason I'm even attempting this because its so hard to find comforters that come down far enough on the sides. Using a queen SPREAD now for this purpose and its about right. I think I'll plan to use a 9" block per Krista's advice. I would PREFER bigger so I don't have to make as many but i hate to lose the design in the process. So I will cut my pieces and then ADD 1/4" all around on each side (and curve) of each piece, correct?