Things You'll Need
Instructions
Begin by spraying a small circle of the spray foam. Start from a central point and work your way out. It should be about 6 inches across. Allow it to fluff up.
Apply another layer of foam to the first layer in the same manner. Continue to do this until you reach the height you want.
Allow the foam to dry completely. Carve the mountain with the knife to create flat areas or caves. Spray with paint or paints of choice. You may also spray a clear glue over the paint and add simulated grass to the mountain.