- Stone Slurry Mix: Combine equal parts lightweight spackle, PVA wood glue, and dark gray latex paint with a spoonful of fine playground sand. Slather it over the entire cardboard prop with a putty knife or rough sponge.
- Dry-Brush Highlighting: Once the dark stone slurry dries, dip a completely dry chip brush into pure white acrylic paint, wipe 90% of it off on a paper towel, and flick the brush across the high points, edges, and raised letters.
- Exterior Sealing: Spray two liberal coats of clear exterior matte enamel sealant over every inch of the prop, especially the underside and ground-touching seams, to repel morning dew and light autumn showers.