First thing I did was take a paper grocery bag and cut it up. Then I crumpled the paper and soaked in water. I then used an Iron set on "cotton" to flatten and dry it.
I spray panted the roofs black after I got the paper glued down then drybrushed each roof with grey to bring out the texture.Here are the six buildings I finished with simple roofs. The com station in the back row has a more complicated roof which I plan to use on some of the other buildings.