A diorama is a three-dimensional model of something much larger in the real world. Dioramas are often made from shoe boxes, but they can be made larger. When making a diorama, it is important to keep a few basic things in mind. Remember, a diorama is three-dimensional, and you should always utilize that aspect. You should also have a great idea before you start.
One of the most popular uses for a diorama is the re-creation of an animal's natural habitat. Start out by picking one of your favorite animals and doing research about its natural habitat. If the animal lives in the desert, use a lot of sand in your diorama. If it lives in the water, use a blue backdrop and some hanging plastic wrap to give it an underwater feel. Find out what kind of animals share its habitat and put a few of them in the scene. Decorate the diorama with any kind of plant or trees that exist in that environment. Try to re-create a scene from the animal's social life, if its species has a structured social hierarchy. Look at a few pictures to get it just right.
Another interesting diorama is an astronomy diorama. Decide what part of astronomy you want to model and study it carefully. One easy idea is our solar system. Study the different sizes, shapes and colors of the various planets, and use small Styrofoam balls to recreate the Sun, planets and many moons of the planets. Hang them from strings and paint the backdrop black. Use a white pencil to create white stars on the backdrop. You could also create a constellation diorama. Hang small Styrofoam balls from strings. This takes careful design, so look at your constellation carefully and design how you will re-create it. Easier constellations include the Big Dipper and Little Dipper. These constellations would need much less stars than a constellation like Orion.
One ambitious idea for a diorama is to craft a cityscape. This can be any city you are interested in, but cities like Chicago or New York have an identifiable cityscape and should be easy to create. Examine pictures of the cityscape and decide which part you want to craft. Use small boxes, such as personalized cereal boxes, to create your basic look. Paint the cereal boxes to resemble the buildings, including doors, ledges and windows. Put these buildings at the very back of your diorama. Paint a road in front of the buildings, and place small model cars and trucks on the road. Place small model trees along the road for extra decoration. Hang small bunches of cotton from the top to create a cloudy sky. Add small models of people to finish up the basic look. Embellish it any way you like.