This is no ordinary planter. It's more like a piece of furniture. A simple box with pieces of trim (any scraps hanging around in the garage?) and legs attached and a fresh coat of paint can make a great filler piece for a sunroom or any other room in your home.
The same simple design can be used with a hinged cover (and I would use more sturdy legs) and a cushion on top for a makeshift window seat with extra storage for toys, blankets or extra books or magazines.