Abstract: A set of four longitudinal, four vertical and four cross bars are secured together to form a three dimensional open frame of a storage unit capable of being closed to a box-like structure by a plurality of flat panels. The longitudinal bars each have a longitudinal T-shaped rib and a T-shaped, longitudinal recess, capable of slideably receiving the rib of an adjacent frame so that a plurality of frames may be arranged and stacked to form a self sustaining structure from which one or more frames or storage units may be slideably removed without disturbance to the remaining structure and units.