This is a very simple structure. Make your usual case bound measurements (a spine and two cover pieces) and then cut an extra cover piece (it can be the same size or a little less wide, this is the piece that will attach to the extra spine and fold over or under the front cover) and an extra spine. Make sure that the extra spine is slightly larger (add the thickness of your book board to it).Then, you take your first three pieces (front and back covers and main spine) and attach them with book cloth (just like your usual case bound) with 1/8 inch between each cover and the spine. After that, you can attach the paper on the front cover like you usually do. When you go to glue the paper on the back cover, make sure there is enough extra to fit the extra pieces as well. These pieces, too, glue on just like the case bound. Measure 1/8 inch from the edge of the back cover and glue down the other spine. Then, measure another 1/8 inch from there and glue down the extra cover. Fold the edges of the cover like usual and glue them down. Now you add the ribbon. Make sure you are gluing it shiny side down (unless you want the rough side to show on the front) and in the middle of the middle panel (your back cover). Make sure the ribbon is long enough to tie in the front.Finally, add in your text block (in the first spine with the book cloth on it) and your end papers. The back end paper will have to be longer than the front so it can cover both the back cover and the extra cover. When you are done, it should look something like this.