Can it be a synonym for "sample of something"?
How about a mock-up of a booklet?
For example, in the world of publishing the book's jacket is the first thing to be produced. The seasonal catalogue of what the publisher will be selling may have mock-ups of that season's books on the front (of the catalogue) - but the photographer just uses real jackets wrapped round random books (or any other appropriate 3-dimensional object). So they are samples for the purposes of the photograph, but they're not samples in the sense of providing anything like the real thing.