As I've posted about before (3D Printing from Google Earth & 3D Printing Mountains), not only can you 3d print train parts and structures, but you can also 3d print your landscapes from sources such as Google Earth and other topographical data.
While this link is over a year old, it provides a list of websites that are still active where you can generate 3d models of different terrains.
Can you imagine being able to 3d print a scale model of terrain from a real world location? If I were to do it using my printer, I'd have to break it up and print in small sections. Then they would be reassembled on the layout. It would be a lot of work, but it is feasible!