I have made a couple of these as wall-hangings.. I looked through my stash for "themes" appropriate for the ones who were to receive them. I had some Harry Potter pieces that worked, some logos from athletic teams, some that looked to maybe be children's books. Keep thinking outside the box and be creative. How about a bowl of fish, a jar of candy? Since one of the recipients has a cat, there was one on a shelf, too. These are fun but time consuming to get the fabrics together!
Now to hope the ones you find will be good size for the spine of a book.