I carry my equipment (Tachi 4x5, 4 lenses, Pentax spotmeter, Toyo loupe, filter pouche) in a 16 qt Target clear plastic box in a Kelty Redwing backpack.

I would like to line the box with foam, such that half the box (where the folded camera goes) would have a thin layer of insulation, and half would have a block of foam or styrofoam into which I'd carve room for the lenses.

Can you suggest a source for close-cell foam (1/2 in and ~2 inch)? Is styrofoam a good idea (I'm concerned it might crumble or break)? Any other experience, tip or suggestion?

Many thanks.