Making a One-piece Swimsuit

June 25, 2012 in Projects


I have always wanted to try sewing a one-piece swimsuit and adding the bandeau with bra cups. So, this tutorial walks you through making a basic one-piece swimsuit complete with bust support! Keep in mind this is a first for me too! The process was really neat and, I thought, fun! Remember, if this is your first or second time making a suit or with a new pattern, don’t give up after the first try, they get better with practice if it doesn’t turn out how you wanted it to turn out! Also, remember, this is the way I put mine together, but, there are other ways to achieve the same or similar results. Share any tips or tricks you have in the comments section!!

The pattern below is what I used and I loved it; unfortunately, it has been discontinued, but, you can still find it online in a few places (here’s one I found). This particular pattern (Stretch and Sew 1301), gives really good instructions and pictures and it has 3 leg cuts, low, medium, and high leg cuts (I did medium). However, if you can’t find this pattern, find a similar one with the bandeau top lining.

1. Cut out swim fabric (buy fabric according to pattern specifications). I have a really long waistline, so, when I cut it out, I had to add some length in the waist, shown below. And, when I am doing a plain fabric, I actually like to line the whole swimsuit in addition to the bandeau, rather than just lining the crotch (but, that’s up to you; perhaps, try it first the way the pattern specifies with only the bandeau and crotch lining).

A closer look at cutting the pattern and elongating it.

2. We are going to start with the bra cup lining. Mark the center bust point with a pin.

Pull pin through pattern keeping pinching the pin and fabric together so that you can remove the pattern and keep the pin mark.

Picture below just shows pulling the pin through the pattern yet keeping the pin in place in the fabric.

Mark the location of the pin with chalk or washable marker on both sides of fabric (top and bottom).

Marks shown below.

3. Set bandeau aside. Ok, this step is kind of a side note, you can purchase bra cups (they may need to be trimmed down and I like to serge them if I trim them down so the layers don’t start peeling apart) or, I had an old bra and just cut the cups our as shown below (sorry, the picture is terrible).

Cups cut out…

I traced cups from another swimsuit.


And cut around my traced mark to get 2 new black swim bra cups.

4. Ok, grab the bandeau lining again and pin cups accordingly to where the bust point marks are (pattern gives good tips here).

This is what the other side looks like with cups pinned in.

5. Stitch around cup (stitching cup to bandeau, making sure not to stretch fabric over cup too much) with a zig-zag (play with your zig-zag stitch before sewing to find the setting you like, write that setting down).

Here’s is what the other side looked like (this will actually be the side that will sit against your skin).

6. Cut out the fabric that sits within the bra cups; shown below.

My finger is pointing to what has been cut out…

What it looks like with cut out fabric…

6. Now, you will sew the plush backed elastic to the bottom edge of the bandeau as specified in the pattern with a zig-zag stitch (I couldn’t find plush backed elastic in time, so, I just used regular).

Here is the “front” side of the bandeau (this will never show, it will be between you and the outer layer of the swimsuit; the other side will sit flesh against your skin).

Bandeau is ready to be sewn into the suit; after we construct it 😀

Here are the pieces you should have.

7.  I’m starting with the back piece.

Pin right sides together to sew the center back seam using either a stretch stitch or stretch the fabric as you sew a straight stitch.

(Now, because I am fully lining my suit, I pinned the front pieces together and the back pieces together (after opening the back pieces out flat); you can baste the layers together if you’d like).

8. Gather front piece at the top according to the pattern.

9. Now, match up and lay the bandeau on the back side of the front piece, wrong sides together (should be positioned as it will be worn).

Here’s a close up of it pinned…

Baste top side edge and armhole.

Also, baste the neckline to keep bandeau in place.

10. Pin side seams (you can sew now with the stretch stitch or stretch while sewing with a straight stitch; I like to pin all and then sew all).

Pin the crotch seam.

Pin the shoulder strap; I took a close up of this one to show that the front and back strap are a little offset because of the way they are cut.

11. You may have already sewn each as you pinned, but, if not, sew all, side seams, crotch seam, and shoulder seams.


12. Serge leg holes, arm holes, and neckline if desired (I wanted to to keep my layers together since I fully lined mine). You can use a zig-zag stitch with your sewing machine if you’d prefer!

13. Now, place elastic in the leg holes, arm holes, and neckline according to the pattern. If you need some help, check out this tutorial at step 12!

As soon as the elastic is in, you’re done!!

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