A wonderful woman taught me how to do this >>> the amazing Joyce Hazen. She is extremely talented. She was in for a stamp convention. Her book is amazing. Mine is still uncomplete. I need to add photos and journaling to it. I used my scor-pal to score the lines. The beautiful patterned paper belongs to The Angel Company™. This book seems endless :)
Think of all the different ways you can add flaps. Just beware that you don't make it too thick that your book won't close.