I have wanted for years to get round to making an electronic hive scale,
glad to hear someone else is doing it. Here are some ideas:
size at least 45 cm square for UK hives to sit on comfortably
reading from about 20kg upto 60kg would suit my needs here
able to be read to 0.5 kg would be enough
battery operated for use in the field, and long battery life
A real luxury would be to have a floppy disc drive fitted with appropriate
electronics so the weight would be recorded at pre-set intervals and I
could take the disc and slip it into the PC to see the results.
Could it be made quite slim so that it could be slipped under a hive just 
for long enough to take a reading? So records could be kept of several
hives.
it would need to be weatherproof.
And very cheap of course!
Bee Biz for february mentions something similar shown at Apimondia,
complete with modem, price not mentioned.
Brian Gant
Buckfast, UK