Made a few books. Figured I'd share the process.
Started off by marking the halfway point down the stack.
Because I wasn't able to get it cut perfectly in half every time, I sorted the pages I had into 3 general sizes
When one of the stacks was roughly the size of a book, I put the shortest page in front and marked every half inch a little bit from the edge.
Glued a piece around the spine to help keep things together