When I started to design books/comics during my research I stumbled across this youtube video that explains simply and visually the process of creating a repeating pattern (or wallpaper if you like).
I think book ends are often overlooked in the design. Children and adults can benefit from the visual cues that can be given within the end book papers. I also think they help the reader slow down and enjoy the book more, which is definately an action I seek to achieve if a book has a smaller page count.
Anyway considering your book end papers is something you really should consider (among a lot of other aspects) when you are creating your book.