I have used these industrial meat packing freezer spacers on sets since seeing them at Modern Props in Venice, CA, in 1986. They work wonderfully in many different applications: they can be lit through and throw wonderful patterns. Our gaffer and electricians on Babylon 5 call them "meat racks," but we refer to them as "freezer spacers." They are made of a strong plastic composite and can be easily painted, drywall-screwed together, or cut. We have used them as walls, ceilings, divisions, floors that can be uplit, and high-tech sci-fi accents.
The cut pieces make great "space junk." I have also used them in the theatre--they can be lit like a scrim, as we did in the production of Company of Heaven at South Coast Rep in 1993. We used them extensively on Babylon 5 the first couple of seasons because they were easy to set up and strike and could be reused easily.
They are a high-tech, low-budget solution to many problems. We stopped using them as much when many other space shows started using them--and when I noticed them as the background for Tom Brokaw on Dateline NBC, I knew they were over. They were now and not future for me. So Dateline ruined the future for me. Still, the other sci-fi shows use them extensively.