You can absolutely stack horizontal carousel systems on top of each other to make the most efficient use of vertical space in your warehouse or distribution center. This is possible by using a Vertical Lift Module (VLM) system, which consists of a series of horizontal carousels stacked vertically and accessed by a vertical lift mechanism. The VLM retrieves and sends the proper items to the operator at the correct carousel level, while the carousels rotate to present the appropriate bin or shelf for picking. This allows operators to access a larger number of items without taking up additional floor space.