I have been so fascinated by observation hives, but have always felt they should be completely functional. I finally designed and built one, with only the most basic of tools.
It is 8 frame, 2 frames wide & 4 high, with the 2 bottom holding deeps (for easy brood transfer). I have not put bees in yet, and I plan to have foundation rather than expect them to figure out where I want them to build. But if you might like to build a hive, I have design plans for a fully functional observation hive built from inexpensive pine lumber and plexiglas.
I also plan to build a super which will clamp on to the top, with a center 1" entrance hole and ventillation above, in which I will have 2 honey frames. That part will be easily removable, separately from the main hive. I believe that will help relieve congestion and maintain a functional hive through the seasons. http://observationhive.blogspot.com/