For this faux metal roof I used Brae's technique (see her lighthouse build). For the paint I mixed my own grey from Americana Neutral Grey and Titanium White. After a couple of coats I finished it with a coat of Satin Varnish. I then mixed a couple of drops of Burnt Sienna into some clear Satin Varnish to create the "stain" color which was applied in various places at the edges and along the joins of the roof. It's subtle, but I like it.