For a long time I've been trying to figure out how to make it possible to build variated medieval cities without having to build each building by hand. I came up with a system of modular design where each part is it's own object. This can for example be a window. This window also contains multiple parts, like frame, window and boards. Then I can export the object into Unity3D and hide various parts of the object as I want. I can also easily change the material of one part without having to build new objects for it.
It's a bit difficult to explain it and if I ever get around to it, I might make a tutorial.
This might not be a very good or efficient way, but it's one way to do it.
I'll upload the files here if anyone wants to use them.
2014-09-28 Here are some quick tutorials I wrote on how I used the modular design:
http://silveralv.blogspot.se/2014/09/export-fbx-in-blender.html
http://silveralv.blogspot.se/2014/09/import-to-unity-3d.html
Thanks a lot, Daniel. Even if it's CC0, I'll fully credit you in my game (which I later plan to release into public domain as well, by the way).
There is an issue with this file and a couple others of yours (like the stairs). It won't extract to a different folder. It gives an error code that 'the parameter is incorrect.' I'm having not issue downloading most of your assets, so it's not something with my extractor.
These are great.