So I've got plans to make some hard-side film holder cases and I'm in search of a suitable padded liner maybe 3/8-1/2" thick. Foam/rubber, whatever would work for items that fit snug. I don't want the holders to bounce around but they need to slide in/out without force.

criteria:
available in rolls or sheets
either peel/stick on or compatible with spray adhesives like super 77.
won't dry out/deteriorate over time

post specific links or product numbers if you've used something suitable.