To start, here's a link to a recipe for the freeform Buttery Books puff pastry sandwiches featured below. They look like old vellum bindings (yet delicious with their ham and cheese pages).
While freeform edible books can be extremely charming and creative, some of you might prefer some structure. There are book molds for this purpose, some old and some new. There are molds on the market for book cookies, ice cream, cake, candy -- pretty much for anything you can think of. Some are open books, others are closed. These leave a lot of room for variety of design. Here is one of the copper cookie cutters I've seen.
You probably have seen the many open book cake pans made by Wilton and other companies. Vintage ones can easily be acquired but they are also still being made in various sizes. It's a good idea to save the packaging if you are collecting:
If you are looking for ideas for book cakes or cookies, I'd suggest that you conduct a web image search for 'book cake'. You will see hundreds of them and they are awe inspiring. Have you heard of Edible Book Day? It occurs every year on April 1 around the world. Here is one cake from a festival that ocurred in Texas:
One of my favorite book molds is the maple sugar mold. These are wooden molds in six parts. They make a full book about 4-5 inches tall. I've seen two, both Bibles. I think that this one is in the Royal Ontario Museum, but need to locate the citation for you. Notice how beautifully carved and book-like it is with its nicely proportioned border and center motif. The one I have is similarly designed, but it has a curved spine and foredge and a dentelle border, a bit more rustic than this one.