As this is a design-related thread, I'll just chuck in a couple of comments in case they're of use to anyone planning a new design.
I don't use a 'hive tool' - never have, although I did make one a few years ago and played with it for half an hour, before going back to my 'tried and tested' kit.
When performing an inspection, I require tools to perform the following 3 tasks:
1) break the propolis seal between box and crown board (inner cover), or between 2 boxes - without damaging the woodwork.
2) enable frames to be moved apart and/or lifted.
3) enable frames to be closed-up together, without squashing bees whilst doing so.
So - this is what I use instead of a 'hive tool':
The blade of the paint scraper is 0.5mm thick spring steel, and bevelled at the leading edge giving knife-sharpness. I have inserted this tool - in some cases many hundreds of times - without causing any visible damage to box edges. In my view this is the perfect tool for breaking propolis seals - bar none.
When conducting the inspection itself, the screwdriver can be inserted between frames at an angle of 15-20 degrees to the horizontal in order to move frames apart, and inserted vertically to lift one frame using it's neighbour as a fulcrum.
Then, when the time comes to close-up frames, the screwdriver blade can be momentarily held between the side walls of Hoffman frames, thus preventing the bees from being squashed between them as the frame walls meet.
LJ