DIY Swimsuit Sewing: How to Make a One-Piece Swimsuit

Hello!

With summer just around the corner, I felt inspired to take on a new challenge: DIY swimsuit sewing.
After years of sewing, this was actually my first time making a swimsuit—and honestly, I wish I had tried sooner!

Swimwear sewing has always felt slightly intimidating to me, especially because of stretch fabrics like Lycra, elastic application, and all the technical aspects involved. But this time, I decided to push past that fear and finally give it a try.

If you enjoy pushing your sewing skills, you can also explore my DIY projects for experts, where I share more advanced creations like this one.

Choosing the Right Swimsuit Pattern

To get started, I chose the Alison pattern by Wisew, a versatile and beginner-friendly option if you want to learn how to sew a swimsuit.
Why this pattern is perfect:

• One-piece and two-piece options
• Multiple bottom styles: high-waisted, briefs, shorty, push-up
• A size range from XXS to 7XL, making it truly inclusive
• The possibility to mix and match fabrics for a unique result

For my first attempt, I chose a one-piece swimsuit—simple, flattering, and finished with a cute bow detail at the back. I also loved the idea of combining two fabrics to avoid a plain result.

Bonus idea: I’m already planning to use my leftover fabric to make a two-piece version!

Swimsuit Sewing Supplies: What You Need

Before starting, I carefully reviewed the supply list and did a bit of extra research. Swimwear does require some specific materials, but nothing too scary once you understand the basics.
For my first one-piece swimsuit, I did quite a bit of research online. Even though the material list included with the Alison pattern was very helpful, some specific supplies are required—like super stretch sewing machine needles and special woolly nylon thread for swimwear.

Pattern Preparation

• The Alison PDF pattern by Wisew,
• A pair of scissors / tape
• A printer and A4 paper

Essential Sewing Supplies

• Swimwear fabric: I chose two fabrics that complement each other perfectly. Honestly, I hesitated for a long time between using the orange for the top or the bottom, so I decided to sketch my swimsuit to better visualize the final result.
  • Plain orange swimwear fabric,
  • Palm print swimwear fabric,
• 6 mm elastic (laminette): Essential for reinforcing seams and ensuring good support
• Super stretch machine needles: Very fine needles that allow you to sew elastic fabrics while maintaining stretch and durability—perfect for swimwear
• Woolly nylon thread matching the chosen fabrics
• Optional: Mesh lining fabric if your main fabric is see-through, for extra comfort
• Sewing machine
• Pins
• And finally, if you have a serger (overlocker), it’s definitely a plus for even cleaner finishes. I don’t have one yet, but I’m seriously starting to consider it…

How to Sew a Swimsuit (Step-by-Step Tutorial)

Follow these steps to successfully complete your DIY swimsuit:

#1 Print the Alison pattern on A4 sheets

#2 Tape the pages together, following the pattern markings

#3 Cut out the pattern pieces according to your size and place them on the fabric

#4 Follow the instructions provided with the pattern. Use a zigzag stitch, which allows the fabric to stretch without breaking the seams

Common Challenges in Swimsuit Sewing (And How to Fix Them)

Even the best DIY sewing projects come with a few challenges—especially when learning how to sew swimwear.

1. Adjusting the machine stitch:
   I highly recommend testing your stitch on a fabric scrap before starting. This helped me find the perfect setting and avoid mistakes.

2. Sewing Armholes and Elastic:
   This step can be tricky and may require a few attempts.
   Pro tip: Baste your swimsuit first (hand sew before machine sewing). This ensures everything is aligned and easy to turn.
3. Using a serger: a real advantage
   Although I successfully made my swimsuit without a serger, it truly makes a difference for this type of project. If you have one, it’s ideal for achieving clean and durable finishes. I’ll definitely invest in one soon!

I’m incredibly proud of my first handmade swimsuit—and it’s been fully tested and approved! This was just my first attempt, and definitely not my last. I’m excited to explore more variations of the Alison pattern.

Many thanks to Wissew for the Alison pattern and to Mondial Tissus for the materials!

What do you think about this fabric combination? Would you try sewing your own swimsuit? Feel free to share your thoughts in the comments 🙂