Get a coloured piece of corrugated cardboard
Step 2: Spine
Cut a thin strip from the cardboard, this will be your spine.
Step 3: Front and Back of Book
Cut the rest of the cardboard in half to make the front and back of the book.
Step 4: Connect the Front and Back to the Spine
Cut of the corners of one side on both front and back, fold the cut corners underneath to make flaps.
Step 5: Stick the Spine
Stick one tab to the spine.
Step 6: Finish the Book Shell
Stick the other tab on top of the tab that was stuck before.
Step 7: Decorate the Outside
Rip a bit if pretty scrapbooking paper and stuck it on the bottom if the book shell.