To help folks get some ideas for building their own terrain, I thought I might encourage what I do- which is look at pictures of other DIY terrain to see where they got bits and what they did with them!
So for this one, two that jump out to me is the two ellipsoid towers on the left and right are deodorant applicators- Right Guards? with all the bits pull out and mounted on some sort of base. The second is that around the center column set it what looks like groups of four would be old keyboard keys! Pried loose, flipped over and used for detail work. I also see a few in other place around the ring- one to the left and two to the right with what maybe hazard warnings.
The offset tower looks like a upside down detergent cap too.