Add some background fabric to both the TOP AND BOTTOM of your leaning book piece. Lay it over your large background rectangle to get a sense of spacing. Our goal is for the top corner of the tipped book to be 1/4 inch away from the edge when sewn. And remember if it’s more than 1/4 inch from the edge we can always trim it.
Cut your background rectangle at an angle. Take out the section of fabric that would have been behind the book and discard. Basically, you want to trim out enough of the middle section so that the left side edge of the piece is gone.
Stitch with a 1/4 inch seam. Press and trim so that the place where the tipping book touch the shelf and touch the next book are 1/4 inch from the edge.
Stitch your tipping book to the rest of the book block with 1/4 inch seam allowance and press.