Steel utility boxes from the hardware store make sleek, modern pots. Choose a range of shapes and sizes. Turn so that the side with holes is at the bottom, and plant with low-growing succulents, such as Echeveria 'Black Prince' (left) and Sempervivum; top with gravel. (We used no. 2 grade grit.) For an exotic centerpiece, arrange several in a tray filled with grit.