Step 1: Stuff you will need.
Any sketchbook this size will work, really, doesn't have to be a moleskine, but they do look nice, and have sturdier builds than others I have found. also doesn't have to be a sketchbook, but the thinner paper in notebooks will make this more awkward than it needs to be.
2. A sharp craft knife.
Whatever colour you like, I used the charcoal/black stuff because it matches my charcoal kindle nicely.
4. Cling film/saran wrap
This will make sense, honest
6. PVA glue/ clear drying thick water based glue
I think it's called craft glue in the US?
7. Some kind of clamps (optional)
8. A bunch of pencils/straight things (also optional)
9. Spray mount or other tacky, non warping adhesive.
Step 2: OK, first thing, stick your pages together
I used a can of Spray mount, but I have a suspicion the repositionable stuff would work better.
anyway, anything that will stick 2 pages together without warping them should work.
do this to allll of your pages, and move to the next step when it's dry.
Step 3: Glue/seal the outside of the pages
You'll want a few layers on the outside here, spread it in with your fingers, make sure to clean the edges, and wait for it to dry before applying again.
so this about 4 times, I'd say? until it seems sturdy enough to hold.
I used the clamps and pencils to make sure it dried flat, and didn't curve too much.