Before a book is real, it first appears as a 'dummy'. That is to say it's a rough version of what will be the finish art and text. I made this dummy book with my printer and tape and lots of cleverness.
Here's a post showing how a book might change and progress between the first sketched out dummy book and the final printed book.
Some of the pictures and words are slightly changed with each new version made as the book evolves.
It's almost more fun playing with the sketches than doing all the finish work, but it's always a challenge trying to keep the sketches loose.