Cray2 Construction queries (utterly random)

Hey guys; So I'm staring at various pictures of Cray2s and I'm trying to work out what the lower covers are made from. I'm referring to the covers that are coloured, apparently, depending on the install - usually red or blue, but images.google has one with a rather garish yellow/green combination. I'm guessing, for what you paid for a Cray2, you got to pick the colours to match your institute. At any rate, they LOOK like they're puffy, like a vinyl covered foam cushion of sorts, perhaps a nod to the Cray-1 power supply seat covers. Is this the case? Also, are the transparent covers on the inner and outer faces perspex/plexiglass or something different? (I can't imagine real glass, but perhaps polycarbonate? Lexan?) I suppose replies should probably be off-list, given the inanity of the question. Thanks all! - JP