1. Cut the lycra trim and strap the length you need by 2" wide for 3/8" swimwear elastic. Seam it to the garment with a 3/8" seam.

2. Here is the front view of the step above. The elastic and band at the side and back were sewn on before the center front .

3. Zigzag or stretch stitch the elastic to the seam allowance, extending it along the edge of the straps.

4. Closer view of the elastic stitched to edges.

5. Wrap the lycra strip around the elastic to the back side, and topstitch along the edge of the right side of the applied band. I used a very narrow zigzag. Stretch the strap and garment as you stitch.

6. Continue to wrap and stitch from the right side. There will be extra hanging seam allowance out on the inside and the back of the strap. You will trim this at the end, but meanwhile, you are certain to catch the underlayer.

7. Trim the excess seam allowance close to the stitching. A raw edge will remain, but it doesn't ravel, it doesn't show, so who cares?