Yesterday I built a very quick model of a freight depot from these two (1, 2) pictures I found online. First I built the model using polygon planes in Maya, a 3D modeling and animation program most often used for movies. From that 3d model, I can get a quick map of the planes that make up the walls and roof. I took those maps into Photoshop and arranged them on an 8.5x11 sized document for easy printing. Using that template, I easily cut out each piece from styrene, no measuring required! Now I just start gluing.