Is it sonotube, the stuff they use for pouring concrete? It gets used in movies when you want cheap cylinder shapes (there are very small sonotubes in the wall of Kirk's TWOK quarters, where they have the little cabinets on the front.) I'm thinking they were used in FOR THE WORLD IS HOLLOW and maybe THE DEADLY YEARS as well for structures on planet surfaces. Had no idea that the Burke people did anything like that (and can't find anything online about them doing that either.) These kinds of stories always make me think of the late Joan Winston's account of being on-set during TURNABOUT INTRUDER. Kelley comes off like an utter prince, no surprise, and it seemed like everybody was pretty nice considering they were all (except I guess Nimoy) going on unemployment next week.