Stacking cells. The Promot CellMaster is a workpiece magazine, which operates with stacks of matrix trays.The stacks can be manually or automatically loaded/unloaded and are moved from one manufacturing process to the next one.The matrix trays, into which work pieces are put down, are typically wire baskets, plastic boxes or metal pallets . The CellMaster moves each container into a position, where the gantry robot can unload the work pieces.