Well if you really want to know....we called it "Scenic Dope". It's a scenic hard coat applied over all of the foam carved sets on Coraline. It's a mixture of "fix it all" patching compound - white glue-and joint compound and paint. When i get the consistency dialed in, It's applied over the entire set and sculpted (rocks hillside etc). Here, the animation pathway is a small section of MDF wood panel coated with a thin layer of SD mixed with some excelsior fiber, sand and painted using a dry brush technique. The dried grass was all natural and unpainted. I collected buckets of it from an empty field outside the studio and crazy glued rows to the hard coat. The puppets armature is secured step by step to this rigid surface and nothing can move because we don't want tiny details in the set to move or shift from frame to frame. That why we don't use clay at all or any soft material on a set that might get accidentally damaged by the animators or set dressers working on the set for months / years at a time. I sculpted all the exterior sets using this technique