i concur, though you seem to have more experience with epoxies than i do

it's easy and cheap to get an electronic strain-gauge balance that measures weights to ±0.05%, though weighing things out that precisely is quite challenging, especially if they are viscous liquids. (note that the rounding error in the densities you give is probably ±½%)

but measuring small amounts of viscous liquids by volume i think you'll probably get errors more like ±10%

powders, like for cooking or for resin fillers, are even less precise to measure by volume