TheoTown

Please read the description before installing this plugin!

This is a small tool (actually, a sidebar button) that allows you to create a heightmap of your city, including the buildings. This allows you to extract a heightmap from in-game worldgen, or to view your city as simple 3D model in blender/any heightmap view website.
Notes:
With highest resolution, which displays all the tiles on the map, the plugin will lag (but it's still usable).
There is a possibility of UI being distorted on low resolutions, please report in comments if this happened to you.
This doesn't create an ultra realistic detailed 3D model of every building in your city.
Since image saving/editing in lua with theotown is either impossible or very complicated, to get a picture of your heightmap, screenshot&crop the output