So my 4 year old niece wanted to be a mermaid this year and, being the good Auntie Lisa that I am, I made it happen. I used Simplicity 2384 for the top, but ended up having to change the fit, shape, and construction method because I added the ruffles and lined everything. The skirt was totally from scratch because I couldn't find a pattern that matched my vision. The bag is Simplicity 4043, no modifications.
It's made from satin, some stretchy metallic costume stuff, and lots of sheer iridescent something or other. Also tons of sequin trim, all hand stitched on. These pictures really don't do it justice, but they were the best I could do in the time I had. I'll see if my sister can return the costume to me for some detail shots in a day or two. I'm really more pleased with myself than I probably have any right to be, but it's only my second garment and I had almost no experience drafting patterns before starting this. It was worth it, though, to see her so happy on her first time trick-or-treating door to door. Anyway, I hope you like it!