Chip - Here ya go:
Construction:
i used sheets of Plastruct "corrugated roof" which i cut into appropriately sized strips. I then overlapped them in standard fashion, using Fabritac Glue to hold everything together. The entire unit is on a self-supporting brace, so that the roof can be removed to replace the batteries (stored in the dormer) that power the hanging spot lights. All framing was done a strip at a time, using Evergreen Rod and Strip.
Painting
I first sprayed the roof with Anodiozed Bronze (dark metallic color), and then highlighted with Aluminum acryllic paint. A dark ink was was then applied, and the whole thing was then sealed with a coat of "dullcoat". Once this was dry, I used a mixture of hand-mixed pastels which was brushed on to indicate rust, aging, and grime.