Level a flat outdoor surface with a layer of dirt. Gauge the direction of the wind and build a firemouth capable of receiving the wind. Lay two levels of bricks to build the back and side walls, forming a square with the open firemouth poised to catch the wind.
Place a grate on top of this square. Lay two more rows of bricks above the grate. Place the kiln shelf so that the walls support three corners. Place a piece of sheet metal across the firemouth to support the fourth corner of the kiln shelf.
Place a square row of bricks along the kiln, leveling as needed with pieces of broken shelves for a uniform height. Lay two more levels of bricks in a diminishing circular pattern. Partially close the top of the kiln with broken shelves, leaving a hole in the middle to function as a chimney.