Good Afternoon Forum members,
I am thinking about building some custom lens cases for my 4x5 lenses 90-250mm (mostly Fujinon CM W series).
It seemed like a reasonable design problem until I started thinking about which kind of foam to use for cushioning.

There is a multiplicity of different foam types, open cell / closed cell / polyethylene / polyurethane / polyester / et cetera.
It would at first blush, seem that closed cell would be the obvious choice. Is this the correct assumption?

One concern that would be problematical is outgassing - Does anyone have any wisdom in this area they would care to share?

Any Spec callout (Mil or otherwise) that I can use to differentiate between the choices?

Thanks for your time and experience.