When I make circles for hand applique, I cut the fabric in a circle larger than the finished circle. With cardstock, I cut the circle out in the correct size. I use needle and thread and sew a running stitch around the edges of the fabric. I pull the threads to gather the edges over the cardboard. I then iron the fabric over the cardstock. (Sometimes I use a little starch or water to hold the shape. Snip the threads and take out the cardboard - perfect circle!