Axiom... there's a lot of way you can use to make sure the foam is holding it's shape.
Have you tried heat ???
A bit of time with a heat gun... might help the foam retain a curved shape (just remember that the foam will still try to keep it's original shape (flat
), so when heating, hold the foam piece more curved than what you're actually looking for)
Anything from hot glue to liquid plastic with fiberglass cloth (or just regular fabric (which will serve the same purpose) will do the trick.
One little trick I've been using when I needed a foam piece to hold a very precise shape is metal wire. I would cut a groove in the piece (usually more than one, depending on the complexity of the shape you're looking for) and would hot glue a metal wire in there. The metal wire needs to be "stronger" than the foam and the hot glue... but once you've got it in there, you can bend it anyway you want and it will help the foam keep it's shape.
If you're going that way... stay away from hangers
I've tried using those, but working that gauge of metal wires without any tools (once it's in the foam, you don't want to scrap your foam finish) is a bit difficult
Anyhow... that was my way of achieving this without compromising the flexbility of the foam and without have to use any toxic-smelly stuff