I suppose another method would be to assume (always dangerous, but sometimes necessary for a SWAG) that bees don't add much weight to the scales when they build wax (although they obviously change it with some salivatory addition which MIGHT add some weight) and weigh a number of scales (say 20 or something like that to average out differences in weight) then weigh a clean empty drawn comb and calculate how many scales that is. That would not take into account cappings, of course, But if you uncapped one frame the same as you usually do (or some number to average the results) and washed and dried the cappings and weighed them, you could add that to the calculations. Of course honey comb varies in thickness and that will change the results...