Before you do that, if you want to play with this idea today, your house is full of circles. Kitchen has dinner plates, salad plates, maybe a platter or pizza pan, all sizes of cups/mugs etc and then if you want a really huge circle, you probably have a round trashcan somewhere that you can trace. I mark (permanent marker which comes off later with nail polish remover even on nice breakable plates and stuff) partial circles ------ quarter circles, half circles, 2/3 or whatever----and that way, I standardize my tracing so it's the same each time.