Here are several variations on the polygonal theme. These examples are all octagonal but there are some hexagonal examples that I made years ago out there somewhere.
There is always a single hinged door with a catch. The door can be lifted off its hinges for those times when the case is being cleaned out and or being replanted. The roof is usually decorated and there may or may not be some decoration just below the "eaves". There is usually a brass finial on the top.
Such pieces generally have a small footprint which is ideal for tucking into the corner of window ledges, and by virtue of being high they can accommodate fairly tall plants like adiantum (Maidenhair fern).
The Type 8 (seen in these pictures in the snow) is generally bigger than any of the others and a little bit more sophisticated. The bright copper effect is new and will quickly oxidise to make the case appear very old.
Click on the image to the right for more photographs ...