There is a wide variety of antique field desks, ranging from small suitcase-sized ones to fairly big chests, like the one general Thomas J.
Until recently, General Jackson's desk was exhibited in the museum of the Virginia Military Institute (VMI).
At one point, VMI gave a licence to a furniture manufacturer to produce copies of the desk, available on the web.
The most common modern field desk is made of resistant plastic composites and steel or aluminium.
There are several variants, but the most common one is a nearly cubic chest whose lid is removed to expose internal drawers and then reattached on the side to serve as a desktop.