Manual pre-workout mixing

I'm interested in making my own pre-workout mix as opposed to buying brand mixes. This would be me buying BCAAs, creatine, powdered caffeine, etc in ingredient form and mixing manually. I've done this before mixing the ingredients on a per-drink daily basis, but has anyone had experience mixing in bulk? So instead of mixing 5g of creatine, 100 mg caffeine, 5g citrulline malate in a drink, I'll look up what the real numbers should be, this is just for illustration purposes mix 500g creatine, 10000 mg caffeine, 500g citrulline in a big jar, sifting them together well, and scooping out the appropriate amount every day? I'm concerned that they won't mix uniformly enough. Anyone have experience doing this?