How to Make a Foam Diorama Base

Draw your diorama design. It is best to have a plan, so you can figure out how much foam you will need and what parts will be made from it.

Cut the bottom layer of the foam and glue it to a wooden base. The wooden base can be a simple piece of plywood cut to the right size. It will be covered by foam so it does not need to be pretty. Cover this wood with a piece of foam the same size to create a uniform foam surface. Cut the foam with a knife, not scissors. Use a water-based construction glue like Liquid Nails or a regular white craft glue to glue the foam You can also use a hot glue gun, but it must be at a low temperature, since the hot temperature can melt the foam and release fumes.

Cut any buildings or high areas from the foam. If you are creating high structures, you can layer the foam further, building them a little at a time. Insulation foam comes in different thicknesses, but even a 2-inch-thick sheet of foam is not enough for a 4-inch-tall hill, for example. Make a bottom layer and a top layer to create the height you need, with middle layers as necessary.

Glue the lower layer of structures to the base. Once these dry, add the next layer, until all of your structures are glued in place. Allow them to dry before working with them or you may disrupt the bond of the glue and have to start gluing over again.

Coat the finished foam with gesso or paper mache. Gesso can be found with fine art supplies, often near varnish or fixatives. Paper mache can be made with newspaper dipped in flour and water. Both of these substances will seal the foam and give you a nonporous surface to paint on to finish your landscaping.