To liven up my bookshelves, I covered cardboard and boxes with stuff I had lying around. I found that old Priority Mail boxes are great for fitting into shelves snugly, so I ripped one in half (Hulkin’ out over here) and covered it with the cool b&w paper from my craft stash. The black design is actually black flocking, so it’s sorta 3-dimensional. I just pushed the covered cardboard back into the shelf and added back books and knickknacks.