I did altered books this year with my students. (sorry no pictures). Here's what we did and then the specific assignment. We took a book, and divided it in half. The first half essentially becomes a 'frame' and "box lid"and the second half becomes the inside container. The first half of the book gets a cavity cut out (think shadow box type frame), but not all the way through...so like only 1/2 of the way through, and the rest of the 1/2 of the pages are NOT cut. So now you have a shadow box about 1-2" deep (depending on the original thickness of the book) that is backed by the 1-2" of uncut pages. You glue all the pages together to form a solid block. The second half of the book you cut out the same size cavity all the way to the back cover, but not cutting the back cover. So you now have hole, that can be filled. You then glue all of those pages together. So now you have a glued together book in two sections, a top with a cavity that is backed, and a bottom with a cavity which has the back cover as the backing.
Specific assignment was to make a time capsule of your life. In the front cavity (the shadow box frame) they had to represent themselves as they are this very moment. They could fill it up with images in the back, and items in the front (think shadowbox), and decoupage the 'frame' front of the book. (we choose to antique the fronts by covering them all up with bits of masking tape, and then staining that..think 60's drippy candles for those of us that old), and in the box part they wrote a letter and put it in explaining everything about themselves, so that when someone 'found' the book years later, they would know who the artist was. They continued the decoupage, or masking tape antiquing all around the book, and 'guilded' the glued together edges of the paper. They were SUPER! We displayed them in our library and got many compliments, including the best of "wow, these are something I would see in a gallery".