Buildings are looking really good. Here's a suggestion that will simplify the roofs. You can use fine sandpaper from 220 to 600 grit and cut pieces to fit the top of the commercial buildings. It's a quick easy way that I think looks pretty good. The gas station and the two lighter roofs next to it, the little building by the empty area, two of the buildings across the street and also the big building in the back all have sandpaper for a roof. Using different colors and grits you can get some good variation with very little effort.
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The roads and sidewalks are just .030" styrene sheets cut and airbrushed. Pretty simple method for curb and gutter on the road.