We've been swamped in here and I've slacked on getting enough foam material in to run a larger order of over the zip prints.  I did email Rick Roth at Pierre's suggestion to get the package on what materials to use from him but no reply yet.  Last run we did for these we used a really thick foam that a foam co. sent us.  It was not the product we ordered (much thicker than what I ordered) but it worked.  I wanted to order enough right now for eight platens and from a source that I can get it reliably from.  
Anyone have a suggestion?
This is for the over the zip printing method where you use a piece of foam that covers the whole platen, no channels for zippers, and just plow right over it all.  The foam compresses and evens things out.