Years ago a friend did a reverse applique type thing with sweatshirts that looked pretty neat. She would sew a piece of fabric to the wrong side of the sweatshirt and then cut close to the stitching on the right side, so the new piece was revealed. The edges of the cut sweatshirt would just curl a little and didn't seem to ravel. They were cute. So I don't think you would really need to worry about the edges if you liked the curly look. Good luck. Would love to see what you come up with.