OK... "cosplay" is a bit of a stretch.
I recently started playing with hatmaking. My millinery skills are limited, but I have managed to create a creditable pillbox, and I can manage the little fascinator-style mini top hats. So I thought, Hey, Wonder Woman pillbox! A cinch, really: blue pillbox, with a metallic gold "tiara" appliquéd on with a red rhinestone star. Naturally, this led to Who else could be created as a hat? Lots of superheroines have iconic symbolism, but how can those symbols be interpreted as hats?
So far, I've sketched Wonder Woman, Supergirl, Phoenix, White Queen and She-Hulk.
Nerd couture. Geek chic. Madness.
I'll post pics as I make 'em up.
Helpful links for hatmaking:
Mini top hat tutorial and patterns (sewn or glued)
Mini top hat video tutorial (no-sew)
Pillbox photo tutorial (some sewing, some gluing)
Pillbox video tutorial (sewn; I didn't have a lot of luck with this, but it really is a nice-looking hat)
Threads magazine issue #153 (March 2011 - I got my copy on ebay)
Hat making books at Amazon -- once you find one that sounds good, you can check your library if you don't want to commit.