Yeah depending on what/which form you are looking for the way of obtaining it will differ. Like for example the arm blades for my Alma cosplay are soild and not meant to move very much so I made them from poster board and duct tape and then coated it all in plaster strips...it needs painting still, but this wouldn't work for say crown clown, but ti could work for it's second gun like form.
~2016 Con Schedule~
Anime Boston, Boston MA
Another Anime Con, Manchester NH
Hisoka Morou (Hunter x Hunter)
Caesar Zeppeli (JoJo's Bizarre Adventures)