T-Shirt DIY Tutorial, I would so do this for a bathing suite cover up. :) I'll attempt this one day...probably will look NOTHING like this though lol

T-Shirt - Cute idea but not much into fringe.I think I'd make it into a crop top and cut off the excess fringe

swimsuits for teen girls - Google Search

You'll find a great selection of bikini tops by shopping Tillys online. Choose from a great assortment here, and worry about the bottoms later.