An example storage module may include an upper support structure, a lower support structure, and a frame. The upper support structure may engage with a corresponding lower support structure of a first different storage module. The lower support structure may engage with a corresponding upper support structure of a second different storage module. The frame may include a first component and a second component. Each component may include an upper portion, a lower portion, and a set of connecting portions. The upper portion may define an upper level of the storage module. The lower portion may define a lower level of the storage module. The set of connecting portions may connect the upper and lower portions. The storage module may also include a set of carrier devices to move in accordance with a movement path and support a set of storage containers.