Duck tape for masking. Use the back of the fingernail to stick it down just on the edge. Spray light coats pointed away from your making. Unless it’s real stiff it’ll probably be a floppy turd. It won’t compare very well to a smaller foamy.
Yeah, gorilla glue is good for what it's good for, but I wouldn't build a foamy with it, it won't flex at all. Some good advice on glues already, and I'll add I use hot glue for foam. Stays flexible, and holds excellent.