Sewing a swimsuit, with or without a serger, requires some planning. Of course, you need to decide what type of suit you're going to make — bikini, monokini, one-piece — and if you're going to follow a pattern. Once the basics are decided, you'll need to buy the right stretch material, needles and elastic. While a serger isn't necessary to make a swimsuit, you should know the proper ways to make a swimsuit using a sewing machine without a serger.
Try on the lining first: Sew together the lining before cutting the fabric pieces for the front / outer material. Any adjustments you make to the lining for a better fit should be measured and applied to the outer material. While making the swimsuit, try it on whenever you have a question. A form-fitting piece of clothing has to be checked often for the shape to look its best.
Neckline elastic: After measuring up and cutting the neckline elastic, attach the two ends with a serpentine or zig-zag stitch. Divide the loop into four quarters and pin it to the middle-front, middle back and two sides of the neckline before sewing. This approach will keep the elastic evenly divided in the neckline.
Measuring a swimsuit: Whether you're designing a swimsuit from scratch or following a pattern, you have to be exacting when measuring your body. Tasha shows how to measure above the bust, over the bust, below the bust, the smallest part of your waist and where the top will end to make a tanktini
While there are numerous types of video following patterns, BritxBrat2Fashion's Monokini Swimsuit tutorial explains how to make a suit based on clothing you already own.