You can find white air-drying clay in craft specialty stores. Use the clay to sculpt a single mountain, or a mountain range. Smooth the clay down into rounded humps to make an older mountain range, like the Appalachian mountains, or form jagged peaks to make mountains like the Himalayas. Once the clay has dried completely, you can use acrylic paints to paint the mountain or mountain range. Leave the tip of the mountains white to make snow-capped peaks.
Polystyrene foam comes in a variety of shapes and sizes; at a craft store, you can purchase blocks of it or ready-made conical shapes. If you purchase a square or rectangular block, you can use a utility knife to carve it into mountains; if you choose the conical shapes, you can round off the tops to make a more natural shape. You can paint the polystyrene foam with acrylic paints to create the mountains, using blue, purple, or gray paints.
You can create a two-dimensional mountain range using cardboard and black matte board as a backdrop. Trace a mountain range out of a piece of cardboard and cut it out with scissors or a craft knife. Place the cardboard mountain range on a workspace covered in old newspaper and paint the mountains with acrylic paint or spray paint. If you use spray paint, take your project outdoors to prevent accidentally inhaling the paint fumes. Let the paint dry completely, then glue the mountains to the black matte board using rubber cement.
To create a more textured appearance than cardboard, you can create mountains using yarn art on matte board. Glue one end of a skein of yarn to the bottom left corner of the matte board; you can use purple or blue yarn. Create the silhouette of the mountain range by gluing the yarn into the shapes of peaks and valleys and fill in the silhouette by gluing lengths of yarn on the matte board inside the silhouette. You can use blue matte board to create the sky and form yarn clouds to create a yarn art picture of the mountain range.