I finished the four swimsuits for my girl-kids. They are pretty cute. The only alteration I made was to add an extra inch in torso length for my girls and to line the entire front instead of just the crotch lining. They did not have them try these on because they are part of their Christmas gifts. I'll use this pattern for years. It goes all the way to size 7.
I did what Kwik Sew recommended for applying the elastic and it turned out great. Here you can see that I serged on the elastic with black thread. Then, I folded it over and zig zagged from the right side. This is the inside.
This is what it looks like from the right side.
These are the original photos from this post.