How to Use Foam to Make HO Scenery

Measure the dimensions of your train table with a tape measure. Cut foam boards to fit the dimensions so that when they are stacked on each other they form a foam plank that is 2 inches thick. Use a utility knife or hot wire foam cutter to cut the foam boards.

Thin white craft glue with water at a ratio of two parts glue to one part water in a cup. Brush the glue over the surface of one foam board with a paintbrush. Press a second foam board onto the first with enough pressure to connect the boards but not enough to create an impression or otherwise distress the board's surface. Hold the boards together for 30 seconds to give the glue time to bind. Repeat the process with the rest of your cut boards until you have the 2-inch-thick plank. Glue all connected boards to your railroad table to serve as the base for your model train set. Wait overnight for the glue to fully set.

Use the base plank to create any underground areas for your train set. Dig pits for anything from ditches to water features using a hot wire foam cutter. Mark the area for digging with a piece of chalk, then turn on the cutter and wait three minutes for it to heat up enough so that it will cut through the foam. Drag the blade of the cutter through the foam along the chalk lines to the depth you desire, and then undercut the foam with the blade and remove foam pieces until you have the exact dimensions of the pit. Sand the pit edges with fine-grit sandpaper and wipe the surface clean with a damp cloth.

Fill the pit with model railroad scenery elements such as model railroad dirt or stone for a ditch or stone pit. Line the pit with the scenery elements and glue it into place by using a medicine dropper to drop diluted glue over the rock or dirt to bind the material to the foam.

Paint the foam pits with brown or green acrylic paints and allow the paint to dry for two hours. Create the appearance of water in your painted foam pits by mixing a two-part epoxy model water mix in a small cut using a wooden stir stick. Pour the epoxy into place and allow it to harden into a watery-looking surface.

Form hills by gluing foam boards together to achieve the height desired. Cut slopes in the foam with the hot wire foam cutter. Glue the hills into place on the foam board base using white craft glue. Paint the hill with brown acrylic paint to give it a dirt-colored primer. Cover the hill with scenery elements such as model railroading dirt, stone and foliage. Glue the elements to the hills with the diluted white glue.