I haven't ever seriously cosplayed like at con or anything, but I am pretty into costuming in general. Halloween is a GREAT time of year for me, haha.
A friend did a book character costume party for her birthday a couple of years back, and I dressed up as Johannes Cabal, one of my all time favorite characters. I got a wig, a top hat, suspenders, a skull topped walking stick, round beveled blue tinted glasses; the works. It was a lot of fun putting together, even if I make the LEAST convincing Cabal in the world, haha!
And I'm super into doing zombie costumes. We have a yearly zombie event where I live, and I get pretty into the special effects. Ripped out throats, exposed teeth, disemboweled guts, stuff like that. I'm not great, but I'm pretty good! I won second place in the costume contest the year before last.
I have this big dream of doing a Madam Zarenyia costume (another character from the Cabal books/short stories). She's a spider demon, so it would involve a lot of chicken wire and papier mache; some kind of harness system; and a series of pulleys and wheels to make the legs actually move at least a little. It would be such a big (and expensive) undertaking, that I don't want to do it unless there is an equally big pay off; and I just don't think a single person would get the reference at any of the local cons my city hosts. It would be cool, but just not worth the stress, effort, and expense, I think. I don't even know where I'd store it after I used it like, once.