Sandy's Fabrics. The elastic is pre-treated so it won't disintegrate in the chlorinated water as quickly as the regular 3/8 elastic you find in most stores.
Pattern: Kwik Sew 3605 (with major modifications to the front of the top)Fabric: ocean/blue mystique swim/dance knit, 90% polyester 10% spandex
Lining: swimwear lining, 90% polyester 10% spandexNotions: 3/8" swimsuit elastic
Here are the pattern pieces below. (I'm taking better notes so for myself so the next time I make her a suit I can remember what changes I made. Hopefully that will save me a lot of time next year.) I used size S for the briefs. But the briefs were a smidge too large so I washed and dried them to shrink them. (I didn't prewash the fabric this time, plus it says line dry.) If you zoom in, you can see the pencil lines indicating the original pattern shape. I added about 3/8 inch to the rise of the briefs in both the front and back pieces.
The top I made in a size M and hopefully it never goes through the drier because it fits great as is. I changed the shape of the back (under the shoulder blade area) so the back side seams will meet the front side seams. If you use this Kwik Sew pattern, you will see that my front top pattern piece looks pretty much nothing like the original. I do prefer the neckline on her floral swimsuit. It ended up being a little too wide on this one and flops open a little bit too much, so I'm going to redraft the scoop neck before I make another suit for her. I've got a shiny silver fabric in queue and also a black/silver polka-dotted fabric, too.