A halter-style one-piece with crossed racerback straps, a lined gusset, and elasticized leg openings — a quick sew from a single main-fabric panel, shown here in a playful shark and jellyfish print.
This swimsuit comes together from front and back panels, a lined gusset, and a matching edging that finishes both the front neckline and the back armholes into crossed racerback straps. Latex elastic keeps the leg openings snug and comfortable for all-day wear.
Cut entirely from a single 50 cm (19.7″) length of main fabric, regardless of size.
Nylon with at least 10–20% Lycra or spandex, or a polyester blend with the same spandex percentage.
Use special STRETCH 65 needles for sewing. Choose a latex or silicone elastic band — avoid elastic made of fabric, as it won't give the leg openings the right hold. All pattern pieces already include 1 cm (0.39″) seam allowances.
| Pattern piece | Pcs. |
|---|---|
| Main fabric | |
| 1 — Back | 1 |
| 2 — Front | 1 |
| 3 — Back edging and straps | 1 |
| 4 — Leg hole edging | 2 |
| 5 — Front upper hem edging | 1 |
| Lining fabric | |
| 6 — Gusset | 1 |
All pattern pieces already include seam allowances.
Cut out all the pattern pieces from the main fabric.
Cut out the gusset piece from the lining fabric.
Fold the gusset piece in half and press.
Fold the front and back panels together with right sides facing. Pin the gusset, right side down, to the bottom hem of the front, then pin the gusset, front, and back together.
Pin the other side edge of the gusset, right side together, to the back, as shown.
Serge or zigzag-stitch in place. Turn the gusset right side out and press.
Press the gusset onto the front panel.
Pin the front and back right sides together along the side edges. Serge it.
Baste the gusset to the front along the side edges.
Measure the leg hole so you can size the latex elastic band. Choose a latex or silicone elastic — do not use elastic made of fabric. Example: for a girl 110 cm (43.3″) tall, the leg hole measures 32.5 cm × 0.95 (coefficient) = 31 cm, plus 1 cm allowance = 32 cm (12.6″).
Mark 4 points to divide the leg hole into 4 equal sections, and do the same with the latex elastic band.
Pin the latex elastic band to the leg hole, matching the markings, and sew in place on the sewing machine — this makes it easier to serge the elastic afterward.
Now serge it.
Fold the serged edge inward and topstitch with zigzag, 3–4 mm (0.12–0.16″) from the edge.
Pin the front upper hem edging to the front panel, right sides together, and sew in place.
Press the seam allowances toward the edging.
Fold the edging over the front upper hem to the wrong side, covering the seam. Topstitch with zigzag 0.1 cm (0.04″) from the edge, then trim the excess allowance.
Pin the back edging (edging and straps) along the armhole and back, right sides together, matching the notches. Sew in place.
Fold the edging over the stitch line to the wrong side and topstitch with zigzag 0.1 cm (0.04″) from the edge.
Trim the excess allowance and press.
Mark the strap placement, 4 cm (1.57″) from the center back on each side.
Sew the straps in place with zigzag stitch, then bend each strap upward and stitch again with zigzag to secure.
