Worth every penny cuts perfect circles BUT has an 8.5" limit. Nancy's Notions has a circle compass that slides on a yardstick (
http://www.nancysnotions.com/product...ick+compass.do). The NN compass can cut a radius as big as the yardstick to which it's attached. It's about $9. I got it on EBAY for 5. Joann's has the olfa cutter and with a coupon the price is reasonable as is EBAY for that. Have fun with your roundabout
.