OK… Lets examine this roof thing. A few givens… New Mexico Northern RR.
In this part of the world ( NM, AZ, UT, CO ) I cannot remember seeing a slate roof, I agree that it would look cool to have one. But this part of the world just doesn’t have access to slate, unless shipped in. AND I have no idea of how to make a weather proof scale version.
Shake shingles were a very common roofing in this part of the world, Readily available, could be made on site, easy repaired. Cheap. I have hand cut a gazillion little shingles, and applied them one by one. But I am older ( maybe not wiser now) and we are running short of the time thing.
Composite: Used by all the local RR’s in the region, Both roll, and tabbed. I have used this on other buildings, and I have more then enough tread tape to do it. Quick and easy for roll, more time for Tab.
Taylor ( guaranteed to never Rust ) Tin. The world manufacturing center is one of the RR’s major customers, shipping and receiving. Readily available, Cheap, never back ordered, Free delivery to building site. Lasts forever.
It’s Taylor Tin!!!