Chances are you have found some photos sent in by the community! Some have even shared their method, in which case I will list their posts below…
David’s Map Printing Method
These prints were made by David, who kindly provided me with the photos and a write-up of his method! You can read that in David’s Map Printing Method post.
Paul Kingtiger’s Old-School Prints
You can see how Paul creates these on his blog: 2-Minute Tabletop (Buildings)