Jeremy makes 3D Printable “strongholds” based on different themes. So far, a borderlands version and elven version.
28mm Modular Buildings Is our latest Kickstarter, Providing you with Modern, Western, Steampunk & Wasteland Modular Buildings Using the OpenLOCK Connecting system for 3d printing. Hayland also makes a bunch of different tiles and scatter terrain as well as Gaslands Car parts. It covers pretty much all genres.
Thunder Chrome has a number of buildings available for your post apocalyptic or Sci-Fi setting.
Modern 3D Models (at this time) that feature walls, vehicles, and other terrain features for a modern wargame.