I finally finished up Maggie's mermaid costume for Halloween, though I still need to come up with some accessories. I used this mermaid tail tutorial, but I made quite a few changes. Some more good tips on using this tutorial from Poot-n-Toots. First of all, the fabric. I used a lizard-print costume fabric for the tail. It's almost rubbery, and didn't fray at all. For the fins, I used tulle. I had to use 3 yards of it (instead of 1) but it was still cheaper than buying organza, plus - no fraying! So much easier to work with.
I used 1 yard on each side of the tail and 1 yard around the waist, folding it into fourths before gathering and sewing it on. Around the waist, I did an elastic casing, then I just tacked the bunched-up tulle down in four places.
The top is just a tube of sequined fabric, with a casing and elastic at the top. We were debating whether to make it into a little tube top or something and Maggie asked if she would be able to pull it down to cover her tummy. I guess that answered that.