Mold-A-Scene Plaster (1/2 Gallon) from Woodland Scenics. Mold-A-Scene is a plaster material that can be shaped like modeling clay, but sets like plaster, without a mold. Its longer setting time allows a modeler to add terrain contours to new or existing scenery. It is excellent for dioramas, layouts and models, as well as volcanoes and other school projects. Dries overnight.