Things You'll Need
Instructions
Cut the pieces of foam insulation board with a hobby knife to the size you want for the base of the mountain. For a small N-scale layout, a base of about 6 inches works well, though mountains come in many sizes so you can use any size.
Stack pieces of foam insulation board until you reach the right height for your mountain. If you use a 6-inch base, make the mountain 9 to 12 inches high.
Glue the pieces of insulation board together with a glue approved for use with foam so you have a block measuring 6 inches in diameter and 9 to 12 inches high. Don't use wood glue because it takes too long to dry. At this point, it will not resemble a mountain. Allow the glue to dry completely.
Cut the sides of the insulation board mountain with a keyhole saw to create the general shape of your mountain. Work your way up the sides, gradually cutting off more foam until you have a general mountain shape.
Sand down the sides of the mountain to smooth it out a little more and put finishing touches on the overall shape of the mountain, such as creating areas that jut out further than the surrounding area or lower, crater-like areas. The insulation board should sand away fairly easily so use caution that you don't remove too much material.
Cut away additional pieces of insulation board with the hobby knife to customize areas of your mountain, adding details such as sharp drop-offs or cliffs.
Paint your mountain with acrylic paint to add detail. Use white if you want a snow-capped mountain. Brown, green and a mixture of the two make good base colors for the mountain.
Spread a thin layer of watered-down white glue onto areas of the mountain that you want to cover with model railroad grass.
Sprinkle model railroad groundcover over the areas on which you spread the glue to add grass to your mountain.
Push model tree trunks into the foam insulation board to position trees onto the sides of the mountain. Glue model bushes or clumped groundcover onto the mountain to create bushes. Add any other features, such as hikers or animals, and glue them into place.