I'm working on my own set of 15mm terrain features to make my 50cm x 100cm table more interesting to play FAD (and Traveller!) on. Right now I'm at the initial stages of making the terrain, and most features are not even primed, let alone fully detailed or painted.
Here is a Celiran ("Lizard") prefab base-camp I'm composing:
There will be three prefab modules (or tents) made from these plastic bottle bottoms, as well as three water/fuel tanks (two made from old toothpick containers and one from an old aloe-vera gel canister and an old electric wire) and two barrels (I don't recall from where they came).
Here is an urban neighborhood I'm building:
The tanks are the same tanks I'm using for the base camp above. I'll build the buildings out of these three washing-powder cartons, either simply cutting windows and doors into them and painting the window frames around them when I paint the models, and/or gluing additional cardboard stripes to them to make rows of windows with actual frames.
I might also be buying a few barrels and crates from GZG to make terrain even more varied.