My three hole punch was spaced perfectly for two of the holes so it was just a matter of centering the dividers and index cards.
I wrote each letter with a Sharpie on the front of each divider.
Then we searched for pictures to fill up the book with. She glued on some we cut from magazines and printed photos. I drew the others.
My son helped her guess what each word started with and then they filled up the book as they went along.