Sure, you can pick up some knock-together set of shelves, but built-ins provide so much more than just a place to stash your stuff. made to rise ceiling high, create an alcove for furniture, or wrap an existing nook, they can add style, charm, and architecture to an interior, all while offering custom storage and display space.. Built in bookcase design plans. diy built-in bookcase reveal (an ikea hack) - ideasstephanie, i love what you did with the bookcase! built-ins are so expensive and you achieved the built-in look for a fraction of the cost!. �