Hmm I like the idea of the Jerry can or big bottle with funnel. Saves the mixer. I suppose a big bottle would be better as a Jerry can may struggle to fit on scales?Funnel is your friend. Tare the empty bottle with the funnel & fill by weight.
Thanks I'll probably go with a jug then, will make pouring it into the bottles easier as the other poster said.
Do you just use kitchen scales? Is a stick blender the same thing you would use to blend soup?