How to Make Faux Rocks From Spray Foam
- 1). Place the cardboard paper or box on a flat surface. Spray the foam onto the cardboard. Keep adding foam until the rock is the correct size.
- 2). Smooth and mold the foam with a putty knife, and let it dry. Add more dollops of foam if necessary.
- 3). Cut edges and gaps into the foam rock with the utility knife. Smooth the surface with sandpaper. The sandpaper also helps give the foam a more grainy appearance.
- 4). Paint the foam so that it will look like a rock. Use combinations of gray and brown paint, with white and black paint to form shadows and highlights.