Instead of painstakingly measuring and marking degrees with a protractor and compass before cutting, I did this: I used my nifty circle cutter to cut out a circle which I then sliced it into quarters (4x90 degree segments). Then I took a ruler and laid it corner to corner (the end points of the straight lines) on the quarter circle. I measured the distance between the points and mentally divided it by nine (9x10 degrees). You can also use a calculator for the division. I then marked off four equal two-ninth (20 degree) sections for the sides of the cone and left the remaining one ninth (10 degree) section for the glue flap. The process may sound complicated, but it's not. The moment you try it, you'll see how quick and easy it is.