The Atlanta-based designer Colleen Jordan got the idea for the planters from the flower pots in the new generation of Volkswagen Beetles. "Putting a plant in a car like that seemed to be contradictory," she tells Co.Design. "A lot of cyclists seem to be plant lovers as well, so the combination just seemed right in my mind." So she began offering made-to-order 3-D printed vessels that attach to a bike frame with an elastic cord. Jordan recommends using a clipping from a succulent or a large air plant. Since they’re made from polyamide, a porous material, excess water drains out of the bottom.