My problem has to do with whether or not to line crates?...

I'm producing three travel crates for a collection of (50+) framed, etchings.

My supplier could not get MDO (after 10 days wait) and I substituted a paint-grade plywood (3/4" maple veneer). I knew there would be disadvantages to not using MDO, but I could not wait longer to begin the project.

My question is whether or not to line the crates, and, if so, with what?

The body of the crates are the mentioned plywood, with 1x4 poplar as binding/battens and 2 inch ethafoam on inner surfaces. Joints are fairly tight: air-nailed, glued and screwed. The crates are to be used as travel crates (and storage), so I'd like to get this right.

All the works are framed, behind glass (not plex) with backs sealed in paper (Not that it pertains here, but all the works will be fitted vertically).

My question: If the crates can be stored with lids ajar (or removed)--do I still need to line them? And, if so--what lining would you recommend? Is there anything suitable that is cheaper than Marvelseal?

Thanks for any help!
Rick