Sweet Little Serged Swimsuit Project

By Stephanie Struckmann

SKILL LEVEL: Intermediate

Swimsuits are really pretty easy once you get the hang of it, and baby swimsuits are the perfect place to start! Make this adorable swimsuit for the little darling in your life, while getting great practice with your Baby Lock serger and stretchy fabric!
Download printable instructions.


    • 4 spools of soft Madeira® AeroFlock thread to complement fabric•
    • One spool of Madeira® Aerofil Polyester sewing thread•
    • ½ yard of swimwear fabric
    • One package of ¼” elastic (suitable for swimwear)
    • One package of ¼” elastic (suitable for swimwear)
    • Find the free pattern tutorial by clicking here


    • Baby Lock® serger
    • Baby Lock® sewing machine (with a stretch needle inserted)


  1. You must create your pattern from a baby bodysuit that fits your baby!
  2. Cut one front and one back piece on the fold. Cut two or three 2” strips for the ruffles on the bum. Cut the length of the 2” strips at double the total width of your back piece to gather.
    1. Finally, for the halter strap, cut a 2” strip that is about 30” long or longer (you can always cut it shorter).
  3. Thread your serger for a four-thread overlock stitch with Madeira AeroFlock thread. A needle threader is very helpful with this soft, plush thread!
    1. Set your stitch length to 2.5mm and your width to the widest setting.
  4. Serge along the edge of the single layer of the casings on both the front and back pieces to finish the edges. Then, slowly serge the two armholes on the front.
  5. Fold the armholes in about 3/8” and stitch in place using a stretch needle and a straight stitch on your sewing machine. Slightly stretch as you are sewing.
    1. Next, fold over your casings 5/8” and stitch down with a straight stitch.
    2. Note that there will not be a lot of stretch stress on the casings or armholes, so I did not use a stretch or zig-zag stitch in these areas, but you can.
  6. Change your serger over to a 3-thread Overlock, Narrow Hem, with a stitch length of 1 to 1.25mm and the smallest width. Hem top and bottom of the long edges of your ruffles.
  7. Gather each ruffle with one basting stitch about a ½” from the top edge of each ruffle. You may not need to gather the eyelet lace strip as it may already be ruffled.
  8. Take your back piece and draw a line with a fabric marking pen where the GATHERED STITCH LINE of the ruffle will be placed.
    1. Hold your back fabric piece up to your baby to judge the placement of this line as to where you want your ruffles placed. Then, draw two lines below the first line.
    2. I drew mine .75” apart, but, you may need to adjust depending on how wide your eyelet ruffle is and the look you are going for.
    3. Just make sure that the hem of the third ruffle is 1” or more above the raw leg hole (to leave room for the leg hole hem and elastic).
  9. Pin the lowest ruffle on first, pinning the gathered stitch line upon your drawn line,and stitch this ruffle down with a narrow zig-zag stitch with your sewing machine.
    1. Follow with the second (this would be your eyelet ruffle) and finally, the top ruffle. Stitch the raw edges of each ruffle down evenly at the side seams to hold.
  10. Measure from side seam to side seam of the bodysuit and cut a piece of elastic with that measurement.
    1. Insert this piece into the back casing and stitch down the first raw edge when it is even with the raw edge of the casing.
    2. Then allow the casing to gather as you continue to pull the elastic through. Stitch the second raw edge down when it is even with the other end of the casing.
  11. Match up and pin your side seams. Baste these seams with your sewing machine first to hold in place with a ¼” seam allowance.
    1. Change your serger back to a four-thread Overlock stitch (2.5mm stitch length and widest width) and serge along the two side seams to finish the raw edges.
    2. When stretched, the straight stitches may break, but, the serger stitch will strongly hold your side seams together while allowing for stretch.
  12. Change your serger back to a three-thread Overlock – Narrow Hem with the same settings as before. Serge both leg holes from the top side to finish those edges.
  13. After loosely measuring your baby’s upper thigh, add ¾” to this measurement and cut two pieces of elastic for the leg holes.
    1. With your sewing machine, about ¾” over from the serged edge, place a basting stitch on both leg holes and gather up slightly to the same length as the elastic pieces.
    2. Then, using a narrow zig-zag stitch, sew your elastic on top of the gathered stitch line (trying to keep the gathers evenly spaced).
    3. After elastic is secured, stretch each leg hole to break the basting stitches.
  14. Change your serger back to a four-thread Overlock stitch with the same settings as before and serge the seam at the crotch.
  15. Secure and stitch down serger thread tails about a ½” down from the end of each seam/stitch line and cut off excess serger thread tails.
  16. Fold your long halter strap strip in half with pretty sides together and long edges even. Serge along the entire long edge.
    1. Turn right side out with a skinny loop turner. Tie a small knot on each end.
  17. And, finally, pull the strap through the front casing (using a safety pin or your skinny loop turner).
    1. Make sure the strap is even on both sides of the casing and stitch a small vertical line in the center of the casing through the strap to keep it from pulling out.
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