[Test-Equipment] Shipping foam?

[davec]

Hello,
I need to ship a large HP rack-mount 3326A signal generator. The 
specs list is variously as 60 lbs, but also as 80 lbs (shipping 
weight). I presume the shipping weight includes the crate it came in 
when new.

I plan to make my own crate from plywood and 2x2's, which I've done 
before. The foam insulation will be that high-density, shiny, plastic 
stuff, which (as you can tell) I don't know the name of. It's very 
resilient and I've seen it molded in many shapes as end-caps for 
packing many pieces of electronic test equipment.

What is this stuff called? Polyurethane? I've seen polyurethane foam 
described, but have found no pictures of it (which would help me 
identify it as what I'm looking for...)

Other ideas for building a crate and shipping such a piece?

Thanks,
Dave