How to Make Fake Stone With Styrofoam

Glue together smaller pieces of Styrofoam to make the base of your fake stone. Use the craft glue like a rubber cement by coating one side on each of two Styrofoam blocks. Press the two sides together and gently pull apart until you see thin strings of glue forming. Press together one last time and insert toothpicks to hold the two pieces together as they dry.

Use the sharp knife to carve the Styrofoam into the shape you want for your stone. You can make the fake rock any size you like, from a small pebble to a large stone. Shave lightly all around the outside of the Styrofoam as you work. You can always cut it down more if you decide to make the rock smaller.

Use the sand paper to help smooth away the small loose pieces of Styrofoam that remain from cutting it into shape. You can save these pieces for later use as fallen rocks and debris if you like. Just glue them into place on the rock you have carved.

Melt away the Styrofoam beads that are visible in most white Styrofoam with a hot air gun. Keep the hot air gun moving as you heat the surface because it is making the Styrofoam melt. Just use it until all of the visible beads are melted and the surface looks like a craggy rock.

Use the pointed end of the scissors to rough up any completely flat sides you have to the Styrofoam. Rub sandpaper over these surfaces to add a little more subtle surface texture. To create bricks or a stone wall, use a sharp pencil to carve out the lines between the bricks. Don't worry about pencil marks. You will be painting over the surface.

Create a mixture of one part plaster powder, one part crafter's glue and one part water. The amounts of these ingredients can vary, but the mixture should be similar to runny paint. Apply a coat of this mixture to all surfaces of the Styrofoam. Allow it to dry.

Paint the surface of the Styrofoam. You can use an acrylic paint or a Styrofoam-safe spray paint, or you can mix powdered pigments with water and apply. Start with the darkest shade you have, usually a dark brown or black. Cover the entire surface of the Styrofoam. Keep the paint a little runny so that it can soak in better. Allow the paint to dry.

Apply a second layer of paint in a slightly lighter color -- usually a dark gray or lighter shade of brown. Apply a thinner layer of this color. Do not fill in the crevices or cracks in the Styrofoam, which should already have a coat of the darkest color paint. Allow the paint to dry.

Apply a third, slightly lighter shade of paint to the Styrofoam. You can mix your second lightest color with some white, or use a pre-mixed color in a light brown or gray. Just barely brush or spray the surface with this color. You want the other colors underneath to be visible. Allow the paint to dry.

Apply a final coat of off-white, pale gray or even yellow paint to the outside of the Styrofoam. Use only a very small amount of this paint. You only want it to serve as highlights on the protruding areas of the Styrofoam surface. Allow the fake stone to dry before use.