I've got some Hirst Arts plaster molds, for making 3D Space Hulk map tiles, and some other industrial Hirst Arts molds, and I've been making plaster buildings, gluing some odds and ends scraps from 40k sprues, and making some industrial structures for miniatures gaming. They make great industrial buildings for battletech! They go pretty well with some resin stuff I painted up as well.
Here's the collection of resin / plastic / plaster structures so far.
I glue the plaster / plastic bits together, then paint it silver
Then wash it citadel badab black
Everything is stand-alone modular pieces like these beams:
That can then slot in beside other pieces to make a larger industrial structure :)