Here is how I use to do it when I did not have a fancy machine to do it for me. I drew a line the exact length I needed it to be(in the correct spot for the button), then made sure the zigzag was at the correct size. Using a zipper foot I would start at the bottom of the line, lining my zipper foot up on the drawn line, sew all the way to the end of the line, make a 90degree turn stitch a 1/4 inch of zigzags, make another turn(90) and just finish as already done, it always worked for me. Good luck. I would probably make a couple of practice ones. But, it is very easy to do.