The 3D buildings OGLE'd from Google Earth are not ready to be 3D printed off the bat. Each building is a composition of multiple vertical volumes that have walls and a ceiling but no floor. By computationally (i.e. hacked up OBJ-file-processing perl script!) copying all of the roof polygons to floor polygons, we got the job done:

"Volkswagen and Google are working together to develop a revolutionary new navigation system."