So I am making a Support cosplay from the game Super Monday Night Combat. I hope to have it ready for PAX East 2013 which is about two months away. I already have lots of parts and pieces made. The chest body armor, orange tunic, blue LEDs, and gloves are each at least 75%-90% done. The problem is that I've run into the hard part. Making his backpack. In reality it is not that big, it is just from his upper back up to the back of the head.
Thing is, I'm kind of struggling with what materials to use. I picked up a large block of Styrofoam that I'm going to sculpt into the right shape.
It is my understanding that to seal it, I need to use Gesso in layers, then sand, then paint. Can I use Spackle instead?
I tried it out with Spackle on a smaller piece of foam, and while I like the way it looked, I found that pressing my nail into it would just penetrate through the paint and Spackle, exposing the white underneath it with no problem. Also, dropping it on the floor made a piece chip off. So it seems a little brittle.
Is there any way to coat the final product with some kind of clear stiffener? Or do I need to change the Spackle to Gesso? Or is that the problem with working with foam? That I just shouldn't bump into anything or handle?
I'm worried because I will be flying to PAX East, and I'll be putting the cosplay gear in a checked on box for my flight, and I know they sometimes handle those roughly. And i don't want the backpack to fall to pieces before I get to wear it. Not to mention bumping it into things/people at PAX.