I sewed these swimmers for my teenage niece, using a striped lycra from Tessuti. The top was modified from the Megan Nielsen Cottesloe pattern. I lowered the front neckline (I think by 1 1/4 inches). I modified the straps to be ties, because I don't have my niece nearby to try them on, and this way she can adjust them to fit. Instead of swimwear lining, I used a soft swimwear lycra that I picked up cheaply from the Alannah Hill outlet when I was in Melbourne.
The boittoms are the Swimstyle Heiress bikini, with the extra coverage hack option. This pattern has instructions so that the elastic is sewn between the lining and the outer fabric, which is a technique used in a lot of RTW at the moment. There is elastic in the waist and the back leg, but not on the front leg. After trying out this technique, I used the same method for attaching the elastic to the armholes and neck of the bikini top. I used a traditional method of applying the elastic on the bottom edge of the bikini top. The Heiress bikini comes with separate pieces for the outer and lining, with the lining cut small enough that it doesn't peek out.