Last week my daughter had "Fun in the Sun" Day with her class. The only problem was, I hadn't found her a swimsuit that fit yet and the one from last season was too small length wise. She also told me, she would have to wear it all day! Her one piece had criss cross straps in the back and she would have to undress every time she had to go to the bathroom. (Mommies think like this.) So I decided to cut the one piece in half! This project was a little scary for me, since I am use to using cotton, not lycra.
There are two rules to remember when sewing lycra.
Rule #1 You can not iron it.
Rule #2 It works best if you serge or zigzag stitch the raw edges, before folding it over to finish an edge.
After cutting the one piece swimsuit in half. I looked at and said, "What have I done!" Then realizing there is no turning back now, I went for it! It had to work! I am showing you a picture of what I did next with the bottom piece. I rolled it over like you would cotton. Not the best idea! It was bulky and hard to sew over the side seams. Now, I know to serge or zigzag stitch first then turn once, not twice. :) After threading the elastic through the casing and finishing the bottoms. I turned my attention to the top.
I serged the bottom first and then flipped the stitch over to topstitch it down. This was a small swimsuit so I knew the top would not roll up. However if you try this and the suite is not snug across the bottom then use elastic again along the seam.
Here are some tutorials on sewing swim suites and "Fun in the Sun" stuff!