If you’re daring enough to wear a bikini top, you may also be daring enough to try making one yourself. We recommend lining your top with a nice swimwear lining. Many patterns will have a shaped seam, very similar to a princess-seam in a dress, that will help create a body-hugging shape. Some patterns may have a bust dart to help create this shape. Either way, we have some tips to create smooth, enclosed seams, that don’t require a serger. Our method also ensures that the lining is secured to the main fabric, so the seams and darts don’t shift around, especially when they get wet.
The methods shown here are not limited to swimwear. They may also be helpful in bra-making, lingerie, and some styles of slip dresses.

What you’ll need:
We picked out a cute, printed nylon spandex swimwear fabric from our store. We also selected a suitable swimwear lining. We also used a pattern that had a vertical curved seam: There are two pieces, one is the centre front, and the other is the side front. We put a notch near the centre front the bottom of the centre front piece, so we wouldn’t get them mixed up. We also had basic sewing supplies on hand including scissors, pins, coordinating thread, and our sewing machine.

The first thing we did was cut out our main fabric. We folded our fabric, lining up the selvedges and pinned the piece in place and then cut them out.

We then repeated the process to cut out the lining.

The photo above is VERY IMPORTANT! It shows from left to right the main fabric as it will go together to make the top. On the far left is the side front (right), then the centre front (right), the centre front (left), and finally the side front (left). Sitting below them is the lining BUT the face (“right side”) of the lining is facing down, because that’s how we want it to be on the body.

Then we took the centre front pieces of the main fabric and flipped them over onto the right front pieces of the main fabric. Then we tucked the centre front pieces of the lining fabric and laid them UNDER the side front pieces of the lining fabric. Then, in the second photo above, we slid the main fabric pieces OVER the lining pieces. So, we have 4 pieces stacked. From the bottom to the top these are the centre-front lining, the side-front lining, the side front main fabric, and the centre-front main fabric. We then pinned all the layers together along the curved seam.

With our machine set to a narrow zig-zag stitch, we stitched the seam with a ¼” seam allowance. We backstitched at the beginning and end of the seam. We stitched from the bottom of the piece to the top. This means that for piece that sits on the right side of the body (shown in the photos) the lining was sitting on top as we stitched. For the piece that sits on the left side of the body (not shown in photos) the main fabric was sitting on top as we stitched. This is very important as we want the seam allowances to point toward the centre of the body.

Once we finished our seam, we opened out the lining and the main fabric to show our finished seam.

We pinned the pieces to a dress form to show how professional the finished seam looks. All of the seam allowances are neatly hidden between the main fabric and the lining.

Alternative method for patterns with lower bust dart:
If you have a pattern with a lower bust dart, you can achieve a similar clean and secure seam. First, we need to cutout the main fabric and lining for the left and right pieces.

The photo above is very important. It shows the main fabric and the lining as they will appear on the body. It’s difficult to tell, but the face (“right side”) of the lining is facing down.

Let’s look at the first photo above. For the main fabric, fold the centre front OVER the side front. For the lining, tuck the centre front UNDER the side front. Let’s look at the second photo above. Lay the folded main fabric pieces over the folded lining pieces.

Pin through all four layers along the dart.

Using a narrow zig-zag stitch and a ¼” seam allowance, we stitched the dart. Start from the bottom of the dart with a backstitch. Do not backstitch at the top of the dart; simply stitch past the folded edge of the fabric. Leave long threads and then knot the threads very close to the top of the dart. For the piece that sits on the left side of the body, the main fabric will be the top layer as you sew (shown in second photo above). For the piece that sits on the right side of the body, the lining will be the top layer as you sew (shown in third photo above).

Here is a photo of one of the finished seams.

The photos above show how the pieces sit on the body. Notice the nice clean finish on the outside and the inside of the pieces.

*Please note that we used a size medium pattern to demonstrate but our dress form is much smaller. That is why the left and right overlap each other.

Now that you have assembled the lined pieces for your bikini top, you can treat the main fabric and lining as one piece as you apply the straps.

Do you think you’ll give this method a try? Don’t wait too long, bikini season won’t last forever!