To make a desert diorama, use a platform of wood or foam board for the base of the diorama. Spray paint the base with sand-colored paint, or use paper in the same color to cover it completely. If you are creating a diorama that has a backboard, make it blue to mimic the sky. Purchase fine sand in a craft store, or you can use outdoor sand if available.
Using a paint brush, spread a mix of water and glue onto the base and sprinkle the sand over it. Remove the excess and leave it to dry.
To create an authentic desert with plants such as cacti, you can use modeling clay for the shapes and toothpicks for spikes. Use tissue paper to create small cactus flowers and brush. You can add small tufts of yellowish grass by using paint brush bristles that are bunched together to create a brushy look, then glued to the base. Add small rocks to re-create boulders that are often found in the desert.
The desert is home to a variety of animals such as snakes, armadillo, coyote and rodents. You can often find these small replicas in craft stores, or if you are particularly artistic, you can make them from modeling clay. Glue them securely to the desert base. To add realism to the sky backdrop, add cotton in wisps or shapes that mimic the look of clouds.