A method and system to create a modular shelving or storage unit. Different pieces are provided which are configured to be joined together (by sliding) without using any adhesive and can form a box. A plurality of boxes can then be joined together by sliding them together to form a plurality of joined boxes. As such, a custom, modular shelf can be easily constructed by a user simply by joining the pieces which are already provided to him/her. In this manner, custom shelfs can be easily constructed which would fit most any area of physical space.