A self-locking assembly comprising: one or more shelves comprising: dividers to define storage bays that are adjacent to each other in a lateral direction and adjacent storage bays being spaced apart from each other by one of the dividers positioned therebetween; characterised by: a lock contained within each storage bay, wherein the lock comprises a protrusion installed adjacent to and in contact with one of the dividers, each protrusion extending within a corresponding storage bay in which the protrusion is installed in the longitudinal direction; and one or more storage units having a width that is a same as, or smaller than, a width of at least one of the storage bays, each of the one or more storage units comprising: an upper surface configured to transport one or more items supported thereon; and an interlocking feature configured to engage with the lock of one of the storage bays to resist removal of each storage unit from a corresponding one of the storage bays, wherein each storage unit is configured for insertion within and removal from a corresponding one of the storage bays in a longitudinal direction, characterised in that the interlocking feature comprises a recess formed on a lateral edge of the storage unit, the recess having a substantially similar shape to the protrusion, so that the protrusion is configured to fit, partially or entirely, within the recess. one or more shelves comprising: dividers to define storage bays that are adjacent to each other in a lateral direction and adjacent storage bays being spaced apart from each other by one of the dividers positioned therebetween; characterised by: a lock contained within each storage bay, wherein the lock comprises a protrusion installed adjacent to and in contact with one of the dividers, each protrusion extending within a corresponding storage bay in which the protrusion is installed in the longitudinal direction; and dividers to define storage bays that are adjacent to each other in a lateral direction and adjacent storage bays being spaced apart from each other by one of the dividers positioned therebetween; characterised by: a lock contained within each storage bay, wherein the lock comprises a protrusion installed adjacent to and in contact with one of the dividers, each protrusion extending within a corresponding storage bay in which the protrusion is installed in the longitudinal direction; and one or more storage units having a width that is a same as, or smaller than, a width of at least one of the storage bays, each of the one or more storage units comprising: an upper surface configured to transport one or more items supported thereon; and an interlocking feature configured to engage with the lock of one of the storage bays to resist removal of each storage unit from a corresponding one of the storage bays, wherein each storage unit is configured for insertion within and removal from a corresponding one of the storage bays in a longitudinal direction, an upper surface configured to transport one or more items supported thereon; and an interlocking feature configured to engage with the lock of one of the storage bays to resist removal of each storage unit from a corresponding one of the storage bays, wherein each storage unit is configured for insertion within and removal from a corresponding one of the storage bays in a longitudinal direction,