I don't have one because I am afraid that I would waste a lot of fabric using one. I made 2 denim circle quilts and cut all of the circles by hand. 306 circles on each quilt...
I used a circle template and marked the jeans and cut them out with a scissors with a spring. I was not in a rush just marked and cut while I watched tv. I could get the most of my jeans material
good luck I like how the circle quilts turn out