STEP 3:Cut 4 pieces of elastic, using ELASTIC GUIDE (5).
Pin elastic to WRONG SIDES of top along sides, having ends even. With elastic on top, sew using a short, wide zig-zag or serge. Make sure to pin the beginning and end of the elastic to the beginning and end of the sides, stretch elastic as needed.
STEP 4: Fold NECK STRAPS (3) and BACK STRAPS (4) in half lengthwise, RIGHT SIDES TOGETHER. Stitch long edges with a very narrow zig-zag or serge. Make sure to stretch the fabric while you sew.
Turn RIGHT SIDE OUT with a loop turner of safety pin.
STEP 5: With RIGHT SIDES UP, lap upper edge of TOP (1) with NECK STRAPS (3), centering strap. Pin in place. Sew the neck straps to the top. Make sure to backstitch a few times. Fold the upper edge of TOP (1) in half. Sew a diagonal stitch, backstitching at least twice. Cut seam allowances close to the stitch. Turn.
STEP 6: Turn elastic to INSIDE on the 4 sides that you stitched the elastic. Top stitch elastic with a medium zig-zag ¼” (6mm) from fold, stretching as you stitch. Keep fabric pulled taut over edge of elastic.
STEP 7: On the bottom of TOP (1), fold over 5/8” (1.5 cm), RIGHT SIDES TOGETHER making a casing.Make sure you don’t close the opening completely; you’ll need it to insert the cups.Insert neck strap in casing using a bodkin or a safety pin.You can either tie the top to the back or to the front.
STEP 8:Optional – Roll the swimwear cups and insert them through the bottom openings.