I have actually thought, "Can this be done? Can I really sew a smooth circle?" - or quarter circle, as the case may be. Well the answer is yes, with a whole lot of pins. Repeat, a whole lot of pins. I tried to pre-stitch the curve using long hand stitches with basic needle and thread but after playing around a bit, I found that a series of pins, placed about 1/4 inch a part resulted in the cleanest curve. No puckers.