Artificial rocks have a variety of uses. You can create fake rocks to be very lightweight, which makes them useful in landscaping. You can also make them to a very small scale for models and in habitats for reptiles. Faux rocks are typically made from spray foam or a concrete mixture, depending on the final result and weight that is desired for the project. Using a spray foam will make the finished fake rock light and portable.
Things You'll Need
Scrap cardboard or paper
Spray polyurethane foam
Snip the chicken wire with wire clippers and mold it into the shape you would like for your rock. Make the chicken wire form slightly smaller than you want the finished rock to be, since the application of foam will add bulk. The chicken wire form will help the rock retain strength and body.
Fill in hollow areas of the chicken wire form using scrap pieces of cardboard or paper. Filling the interior of the form will allow you to use less foam and keep the shape of the rock.
Spray thin, even layer of foam around the entire structure.
Wear gloves and apply a second layer of foam. Shape the foam with your gloved hands to achieve the look of rock that you would like. Copy a real rock or photo of a real rock when shaping the fake rock. Work quickly while the foam is still wet.
Allow the foam to dry completely according to the manufacturer's directions.
Paint the rock to protect the surface. Select a variety of colors to add variation and depth to the fake rock. Use a latex paint for indoor rocks, or exterior paint if the rock will be outside. Paint the colors on in layers using a sponge to create texture and blend the colors together.
Look at an actual rock or image of a rock during painting to help duplicate the look.
Follow the manufacturer's directions when working with spray foam and paint.