Almost 30 years ago, Sue Fox, started making leotards, and I will guide you according to her master technique. Gymnasts who train competitively know that a leotard has to fit perfectly to outstand the 30-40 hours per week of training and competition. You want to be comfortable as you move, flip and twist in a leotard at practice or competition.
Sue Fox would use her daughters bodies, who trained like so, to tweek her patterns to create a gymnastics leotard that would fit perfectly and not have to be picked and pulled during and after every skill. It took several tries, but she made a masterpiece! I suggest finding a gymnast who can be a guinea pig in your creation process to give you feedback on the fit. Don't get discouraged if it takes several tries.
The process begins with hand picking the fun and trendy lycra fabrics. Today, thousands and thousands of fabric supplies exist and come out with great fabrics all the time. Buy the yardage depending on the quantity you will be making. It usually takes about a yard or so per leotard. Allow yourself extra for mistakes, but a yard should be a good place to start. Next, cut out the leotards by size and style. This is done with a hand or electic blade, depending how many layers are on the table. The fabric is layered carefully and the pattern is weighted down on the fabric to keep the slippery lycra from moving around.
Put the seams together on an industrial serger with thread that coordinate the fabric. Sew it together outsides facing in, making sure the ends match up perfectly. Pin together first if you are not used to sewing lycra fabric, it can be very slippery to work with. Next, use a mid size elastic to sew around the arms, necks, and legs. There is an art to how much you pull or don't pull the elastic, depending on what part of the body needs more security. This step is vital in the form of the leotard. After the seams and elastic are complete, the gymnastics leotard should be topstiched using a topstitcher. This is done by folding over the elastic, and using a zigzag stitch to create a nice finished look. To complete, just snip any lose threads, and wallah! Get flipping!
It is quite an amazing process! Have fun and enjoy. Let me know how it turns out!