A stackable shipping unit includes a plurality of individual components that may be partially assembled, then packed with items to be shipped. The shipping unit can then be fully assembled, and placed on a pallet. The shipping system may include trays that can be used as either a base or a lid. The unit includes vertical components that are generally U-shaped in plan view, and sized to fit closely within the trays in pairs to form a “H” shape in plan view forming a pair of shipping spaces. Additional U-shaped vertical components can then be assembled to close off the shipping spaces, and a tray can be used as a lid and positioned on top of the vertical components to form an assembled shipping unit.