So, having a set of scales at work with a resolution of 0.001g, I used them to measure out quantities of various chemicals and photographed the size of the little piles next to a 5p piece. So if you want to know what 0.25g, 0.5g, 1g or 2g of Calcium Chloride, gypsum and Magnesium Sulphate look like, here are the pictures -
Larger pictures at: http://www.fuzzyblobs.com/gallery/main. ... temId=3312
Calcium Chloride
Gypsum
Magnesium Sulphate
To use, simply make a little pile of chemicals that looks like the one in the corresponding picture and it'll weigh about the same. I've no idea how accurate this will be, so use at your own risk!