A modular bookcase in cube format means you can start small and add as your collection grows without replacing the whole unit. Cubes stack vertically and horizontally so you can build exactly the footprint you need. Each cube holds a manageable amount of weight which matters when you are stacking books. The repetition of the cube shape creates order even if your shelving is visually varied. You can fill some cubes completely and leave others partially empty for balance. These are the modular bookcases in cube format that grow with your collection without looking like storage that got out of hand.