Step 8: Adding a pocket (optional)
If you choose not to add this pocket, just cut out a rectangle that is slightly smaller on all sides like pictures 2 and 3 and paste it on so it covers up the bare heavyweight cardboard. If you do choose to make a pocket, you'll still need to cut the same size square.
First, material: I chose bristol board because it is exactly the weight you want, and I had a bunch laying around. Since you'll just need a bit for this step and a bit for a later one, buying a whole pad does not make much sense. Cereal box cardboard would work as well or an oak tag or a manilla folder. Anything firm should do the job.
You'll want to have a pocket that is properly secured and stays in place, so that means it needs to have a lot of surface area to apply glue. For a diagonal pocket like mine you can see the shape I've used in picture 5. To make this shape, you first decide the size of the pocket you want then add the tabs to the overall size then cut (you want it in once piece). Crease the tabs. Next cut the corners off the bottom and side tabs, see image notes. I left the top right one uncut for style.
You will then need to cover you pocket so it is not white. Again I used blue to make it blend in, but color choice is yours. Make an outline of your pocket (full size with tabs) and then put a half inch border around it and cut out that shape in your paper.
You will next need to make it so you can fold your paper over the pocket to fully cover the white up. To do this, cut triangles out at the corners just like you did to cover the front of the book. Please look at the pictures, the give close-ups and necessary details.
Now you can glue it all in place! first glue to cover of the pocket on the pocket. Re-bend your creases on your pocket. Now, remember cutting out that rectangle? well the ideal size will fit in your pocket, you will need to adjust by trimming. You can see in picture 9 how it fits in. And 10 is how it is supposed to look when done. Whew! big step