The sharp V neck on the Laminaria swimsuit is a bit tricky to sew. I recommend trying it at least once on a scrap of fabric before you do it on your actual swimsuit. If you find this too hard or don’t want to bother you can always sew the soft V neck instead! So why are we even doing all these weird fussy steps? It effectively adds a seam allowance to the center front V so that you can sew elastic to the edge and turn it to the inside without stretching the center front.
The first step is to stabilize the center of the V. If you already basted the body to the lining along the center front that should be enough. If you haven’t, sew for a few inches on either side of the center V 1/4″ from the edge using a straight stitch and pivoting at the center front.
Snip the center V to right above your stitching (but not through it!).
Take a scrap of fabric and place it behind the center V with right sides up. Stretch the center V apart so that the snip forms a straight line (or as straight as you can go) that is 1/2″ long. Use a very narrow zig-zag to sew the V to the fabric scrap. Don’t stitch beyond the 1/2″ of the snipped center. The image above shows what it looks like from the outside and inside.
Trim down your fabric scrap on the sides so that it is the width of the zig-zag stitching (1/2″). Also trim it on the bottom, below the zig-zag. The image above shows what it looks like from the outside and inside.
Cut your elastic to the length for your size written in the pattern. Trim one end of each piece so that it is at a 45 degree angle.
Pin and then sew the elastic to the wrong side of the front V. It doesn’t matter exactly where it ends on the top of the front V (where the straps will be attached) because the excess elastic will be trimmed from the top of the V- it can abut the side elastic (as pictured) or both the side elastic and the neck elastic can overlap at the top point. The angled ends of the elastic should abut at the center V.
In the end, after you have turned your elastic to the inside of the body and stitched it down , you can trim the rest of the scrap down to the width of the elastic.