A project I had in mind from before I got my 3d Printer. I found this site (http://jthatch.com/Terrain2STL/) that lets you create .stl files from topographical map data. I wanted to create a 3d map of the landscape of my hometown, Sudbury, Ontario (I was feeling homesick for interesting geology). The landscape in Sudbury was formed by a meteor strike approximately 1,849 million years ago. https://en.wikipedia.org/wiki/Sudbury_Basin
I've only printed it scaled down to 20% and 50%. I might in the future try and do a multicolour to make the lakes stand out, once I figure out how to make the main crater not be on the same layer, as it is not a lake.
My city limits stencil jpg.
This ended up being more work than I expected. First step was to get an stl file from this site :http://jthatch.com/Terrain2STL/ It took a bit of trial and error to get the right selection, and I used the max setting for vertical scale to accentuate the landscape features (I also did a slight vertical scale increase in 3d builder to further accentuate the landscape). Once I had the stl I needed to make a way to cut out the city limits. I gabbed a screen capture of the city limits and traced them in Photoshop, then did a fill to make a 2 colour outline. Using microsoft 3d builder I imported the resulting jpg, setting it to invert without texture. Then I scaled it up vertically and saved it as its own stl. This is where it stated to get tricky. I opened the Sudbury stl, and imported the stencil, laid it out over top and lined it up as best i could, and made sure the stencil went right through the map, and did a subtract. after about 5 minutes it finished and looked like it had worked, but left errors. Doing an auto repair in 3d builder fixed the errors but left artifacts all over the map. Much trial and error led me to eventually using blender (and meshmixer, and meshlab, and netfabb basic, and probably something I forgot) to do the subtracts in small stages, slicing up the stencil into quarters until I was left with the Southwest and northeast corners left to cut out. Eventually by progressively reducing the cut size I got to a working file. I'm very new at 3d design and am teaching myself from scratch so I'm sure there is an easier way to do this part, but I don't know it at this time. In the end I ended up with an .obj file that prints rather nice, especially once I nailed down the extruder temp for the filament I was using to avoid stringers.