How to Make a DIY Reversible Swimsuit

Draft Bottom Pattern: Back

To make the pattern for the bottom of the swimsuit, trace a long straight line on your paper. This is the fold line. Fold a pair of your underwear in half, lay the folded edge on the fold line, and trace around it on your paper. Add 3/8-inch for seam allowance on the top, side, and leg hole. You don't need to add a seam allowance on the folded edge or at the crotch.

Draft Bottom Pattern: Front

Refold the underwear so that it's only folded along the front center. Place the folded edge on the fold line with the crotch lining up with the crotch from the traced back piece. Again, add the seam allowance like in the previous step.

Cut Out Bottom Pieces

Cut out the paper pattern piece and lay the fold line on the folded edge of your fabric. Cut out one piece from fabric A and one from fabric B. You can use scissors or a rotary cutter for this step.

Sew Around Leg Holes

With right sides facing, sew around the leg holes, leaving about a 1 1/2-inch section unsewn on the back of one seam. Sew with a stretch zig-zag stitch and a 3/8-inch seam allowance.

Sew the Matching Sides

Match up the side seams so that fabric A is with fabric A and fabric B is with fabric B. Sew the sides. Be sure to sew across the seam allowance from the opening you left in the leg seam from the previous step.

Mark the Top Edge of the Bottoms

Turn the swimsuit bottom right side out. Use sewing clips or pins to mark the top edge of the two front layers. This shows which fabrics to match up for the next step.

Roll the Bottoms for Sewing

Roll the bottom part of the piece, then separate the marked fabrics and bring them around the rolled part. When the marked fabrics meet each other again, everything else should be tucked inside and you should have the right sides facing. 

Line up the side seams again, making sure that the right sides are facing each other. Pin or use a sewing clip to keep the fabrics together.

Sew the Top Edge and Turn

Loosely baste the top edge, close to the fabric edge. As you work your way around the top edge, you can pull the rolled part through what is like a tube. Continue adding basting stitches and pulling it through. Repeat this same process as you sew around the top with a stretch zig-zag stitch. 

Hand Sew the Opening Closed

Turn the swimsuit bottom right side out through the gap in the leg hole. Hand sew the opening closed with a ladder stitch.

Sew the Strap for the Top

To make the top piece, start by measuring around your torso, just under your bust line. Add 12 inches to that measurement. Using a rotary cutter, cut two strips of fabric 1 1/2 inches wide by the length figured above. Sew the two strips with the right sides facing. Turn the piece right side out and hand sew the end closed.

Cut the Swimsuit Top Pieces

Choose how wide you want the bottom of the triangle pieces for the swimsuit top. For the sample, the pieces started at 9 inches wide. You can adjust this based on your size. If you're unsure, measure a suit you currently have.

Fold the fabric in half and mark 4 1/2 inches away from the fold (or half of whatever size triangle base you're using). On the fold, mark 27 inches up from the base of the triangle.

Use your ruler to cut an angled line from the two markings. Cut out two triangle pieces from fabric A and two from fabric B. You may want to use the first cut piece as a pattern for the rest of the pieces.

Sew the Swimsuit Top Pieces

Match the bottom edge of a triangle from each fabric and sew. Measure and mark 1 1/2 inches up from the sewn edge on each side of the triangle. Sew from the marking up to the triangle point, then back down to the second marking. Leave the two openings. Repeat with the second set of triangle pieces.

Hand Sew the Edges at the Openings

Trim any excess fabric to reduce bulk, then turn the triangle pieces right side out through the side openings. Hand sew the raw edges under the openings, stitching with a double running stitch. 

Head Out in Your New Swimsuit

Slide the strap through the openings on the triangle pieces and your DIY swimsuit is ready to wear. You can wear the suit with only one color showing, or you can mix and match the top and bottom for a fun and playful look. All you need now is a matching cover-up!