Put together a single item from a number of individual pieces.
Remember that sweet diorama you made for elementary school history class? The one that portrayed the Battle of Tippecanoe with nothing more than some well-placed construction paper and a shoebox? Well, as a Dioramist, you still make incredible creations like that, except now your supplies have been upgraded considerably, and you make genuine pieces of art.
For those not in the same elementary school history class, a diorama is a 3D, full-sized or scale model of a scene or event, usually historical. Dioramas can appear in science, natural history, or military history museums (and, of course, in classrooms everywhere).
Your job as a Dioramist is a lot like that of a Model Maker. In fact, many Dioramists get into this field as an extension of their model making. You still spend your days creating models, but instead of making individual pieces, you create entire scenes.
To do this, you begin with a subject. A lot of dioramas portray wars or military scenes, but you can just as easily show off animal habitats, ancient peoples and their ways of life, railroads, or entire states. Basically, anything that you can turn from a 2D photo into a 3D model is fair game.
The purpose of a diorama is to educate people. Because of this, most of your commissions will come from museums, historical centers, or Book Publishers. You can always make dioramas for your own pleasure, but you should be aware they can be pricey to make and are pretty specialized pieces, which can make it hard to find buyers.