Aahh what a fun one! What cosplays have you already done? Do you do any sewing or do you buy the costumes?
I haven't done any dot hacks, but I've cosplayed from Pokemon, Durarara, Attack on Titan, Legend of Zelda.. I don't have any sewing knowledge unfortunately, so I've cobbled the outfits together via ebay and thrift stores. It works, anyways!