A couple of our Association members have ones very similar to this which we take to the various events we attend .. they work very well but, obviously, you need a nucleus of bees available to put in it ... they just transfer the frames from the Nuc into the Obs box for the day - the bees don't seem to mind being confined. Ours have a mesh panel in the top which allows people to smell the bees and when it has been warm a mist of water through the mesh seems to help. A cloth cover when they are not being observed helps as well.
http://www.ebay.co.uk/itm/Observati...843?pt=LH_DefaultDomain_3&hash=item1e9db7cafb
The photos show the construction very well on this listing - perhaps you've already seen it ?
I've been wondering about a similar sort of thing, but just
an "observation top" for a standard nuc.
Bees can live in the same nuc (with standard roof rather than obs top) when not on show.
Before going to the show, the frame with Q is removed from the nuc and inserted into the glass-sided replacement roof, a space-filler (frame feeder?) goes into the nuc to replace the Q frame, and the tall frame-showing lid replaces the roof.
On return, the Q frame comes out of the glass and retakes its place in the body of the nuc, and the standard nuc roof goes back on. The empty glass section can be taken indoors and repolished before the next outing.
The "observation top" would be rather similar to (maybe even modified from) a frame show case, but with QX mesh below and a (coverable) mesh vent above for air and water-misting.
In short, use a standard nuc as the base. Only craft what you really must.
Obviously, there would have to be secure attachment of glass top to nuc, and secure closure of the nuc entrance. For which reasons, a poly nuc might not be the best starting point ...
Strikes me as minimum hassle both to make and use.
But it doesn't seem that others go this route.
Which makes me think there must be some obvious drawback that I'm missing ...