Hi:
 
Norman Gary published a nice set of diagrams for a larger observation
hive.
 
The Dadant unit and other small hives are hard to manage and to keep from
swarming.  2-frames wasn't much better, although these units are easy to
take to schools, fairs, etc.
 
For year round obervations, I prefer 3 or 4 frames.
 
One mistake that I made was setting the glass into a rabbit.  Bad idea,
better seal to keep bees in, but they glued it in so tight that you
couldn't get it out without breaking.
 
I follow Norm's idea, surface mount the glass and hold it in place with
mirror clips.  Then you can cut around the glass with a sharp knife, if
needed, to free the glass.
 
Be sure to incorporate an easy to insert plug for the entrance if you keep
the hive indoors.  When you do need to replace a frames, remove queen
cells, etc. you can readily take it outdoors to work.
 
I think Barry Birney has some diagrams for the style hive that Norm
produced.  Somewhere buried deep, I have the diagrams, but not sure where
I put them.
 
Cheers
 
Jerry Bromenshenk