Draw or trace the design of your prop on the polystyrene foam. Using a permanent marker works well, as pencils or pens easily damage the foam. If making more than one prop, try to arrange the drawings on one sheet of foam to reduce waste.
Use a jigsaw to carefully saw the props. Follow the lines of the drawings as closely as possible. Work slowly with jigsaw and try to make one long continuous cut instead of starting and stopping the saw repeatedly.
Vacuum the cut pieces of foam to remove any particles of dust and foam. If you will be painting in the same area, also vacuum the workspace to remove any tiny bits of foam.
Prime the props with a can of spray primer. Do not skip this step. It will prepare the foam for painting by creating a smooth and dull- colored surface.
Paint the props with acrylic or enamel paint. For intricate designs you may wish to draw the design on the primed foam cutout with a light- colored marker. Cover the markings with paint. Use stencils for lettering, if needed. Allow the paint to dry overnight before using.