Whether you want to create a backdrop for a model railroad or some artwork for your home, making mountains out of foam board is fun and relatively easy. The design of your foam peaks is limited only by how high you're willing to let your imagination climb.
Sketch out what you want your mountains to look like on paper. Experiment by drawing jagged mountains and smooth peaks to see which design fits your taste.
Rough out the design of the mountains on a piece of foam board. Lightly draw what you sketched on paper, making sure that the drawing is light so you can easier correct any mistakes.
Before you start cutting, clean the foam of any stray pieces left by drawing on and handling it.
Begin cutting from the outside to the inside. Cut all straight lines first and work your way into the detail work. Use a sharp blade so the foam won't rip. Once the outside work is finished, hold the knife handle close to the blade and use the tip to create the details.
Give each piece a second look to make sure that everything is cut to your liking. You can use a fine-grain sandpaper to smooth out rough spots on the mountains and give them a blended appearance.
Experiment with different kinds of paint on a separate piece of foam to see which results you like best. Theatrical paint works best on foam board, but can be a bit pricey. Alternative paints such as spray paint can be used; however, it can warp and dissolve the foam.
Once you have chosen the colors and type of paint, you can begin painting the mountains. Blending grays with whites will give the appearance of winter mountains, while greens with browns will create a more summery look. Thicker coats will keep the foam saturated, as it absorbs faster than with paper.
Dry the foam boards at least two to four hours before handling them, making sure that they are in a well-ventilated area and away from high heat or cold temperatures. Once they are dry, display them as you wish.