craftgrrl | gary the snail costume

i want to dress up as gary the snail from the 'spongebob squarepants' cartoon. have any of you seen the 'sleepy time' episode where spongebob invades his friends' dreams? he goes into gary's dream and gary is in a humanoid form wearing a cape. where a human's head should be is gary's head AND snail shell. i want to be gary in this humanoid form.

i am thinking about decorating a hard hat or hockey helmet as gary's shell and head. if i painted the helmet though, the paint would probably crack and peel off. any suggestions on how to do this, or other ways to decorate it?

thanks!