Dad, just be aware that you don't need to cut through the plastic all the way. If you get a good scribed line in the plastic it will just peel right out without cracking. The Ofna cutter helps you get the perfect circle, but you still peel out the material. I have also seen a good square-ish hole made by drilling 4 corner holes and connecting them with straight cuts at tangents to the holes. It makes a nice square with rounded corners. Chances are someone at any given race will have an Ofna cutter if you ask around.