. . .well, at least part of the chimney made it do the garden. When we remodeled our home last year we took out a fireplace. We held onto the metal cylinders and finally we re-purposed them for the garden as planters.
My hubby used a reciprocating saw to cut them to the height I wanted. A couple of coats of spray paint in bright, spring colors was the next step. We buried them several inches into the ground and filled them with potting soil. They provide an unexpected height and color punch to the flower beds.
I planted succulents, flowers, and flowing grasses. They really look great. Your local hardware store should carry different sizes of ducts so you can do this project too. Let me know how yours turn out. ~Rhonda