Fake rocks make a stage set look more realistic. They are fairly easy to make and are much easier to move to the stage and position as desired than real rocks. The materials needed are available at craft or home improvement stores and are easy to work with. Work in a garage or on the patio to prevent making a mess in your home or damaging furniture or floors.
Cut a large piece of Styrofoam into the desired shape of the rock. Use a sharp filet knife, which helps make a precise cut. Stand back from the rock and make adjustments as necessary.
Paint the foam the desired colors. Gray, brown and green are good options that blend and create the look of a rock from the audience seating area. Use a picture to help guide you, which prevents having to start over.
Allow the paint to dry completely. This prevents smearing of the paint, which can alter the finished look. It also keeps paint from rubbing off on your clothing or car as you transport the fake rock.
Create a rock mold out of mesh. This allows you to get a more realistic look because you are able to make indentations and cracks that naturally appear in the rocks. Bend and manipulate the mesh until you have reached the desired shape and size.
Cover the inside of your rock form with packing tape. This helps it hold its shape while you make the fake rock.
Mix the cement. Using a bucket and mixing stick, stir together the Portland cement and water as indicated on the package directions.
Apply the cement to the mesh rock form. Use a trowel, and distribute the mixed concrete to cover the mold. Smooth the cement or leave parts of it rough to create a more realistic looking rock. Allow the cement to dry completely.
Remove the mold. Bending and pushing on the mesh, gently extract it from the underside of the rock. This makes a hollow rock, which is lightweight and easier to transport.
Paint the rock. The dried cement may keep you from having to paint the entire rock. Add color as needed to make the rock look realistic.
Cover the surrounding areas in your workspace to keep them free of Styrofoam or concrete dust as you work.
Lay out a large drop cloth or tarp to work on, which makes cleanup easier.