Gale Force Nine rubble, washers, & clippings from plastic sprues added to them, along with the usual sand. The exposed iron supports are sections of cocktail stick. It doesn't show up that well in these photos, but the bases are drybrushed up through grey, whilst the walls have more of a blue tint to them - I want to keep my revamped Necromunda scenery collection quite muted in tone. I tried-out some graffiti - little more than tags - but am moderately pleased with the outcome. I'll try some more ambitious designs on larger sections of wall in the future.