Abstract: Modular storage systems employing discrete one-piece stud-like fasteners for readily mounting one or more storage bins onto at least two spaced apart support rails. The stud-like fasteners are inserted through a storage bin's hanging slots from its rear side into the storage bin cavity in an opposite manner to hitherto employed fastening screws. Kit for assembling a rectangular rigid support structure including an upper spacer and a base spacer for spacing apart a pair of vertical support rails. The spacers include spacer ends with integrally formed inter-engagement arrangements for mechanical inter-engagement with support rails. The inter-engagement arrangements include one or more integrally formed projections intended for insertion into the support rails. The spacers are preferably rigidly assembled from a left spacer member and a right spacer member by a screw, a snap-fit, and the like.