The rubble terrain pictured here was a simple process, but it adds a bit of flavor. In simplicity, it uses the cut out of a cereal box as the basing, with some dark sand. Small rock croppings were added to the sand by spare pieces of plucked foam left over from other terrain that I'd owned. In order to solidify the cardboard and keep the sand from shedding off, it was all sprayed with elmer's glue in a spray can. The outcome is four pieces that resemble that of down below. Typically I use this for difficult terrain and occassionally as light cover with a +2 bonus to defense.