I think the point that you have missed entirely is that we are grown adults building plastic toys.   Doing so gives us satisfaction for a variety of reasons.   Ultimately, every penny spent on kits, tools and paints is "wasted".   However, you seem convinced that you are among the few, if not only, model builder that understands how to do this correctly.  

Seriously, I don't care if you want to build glue bombs and paint them with latex.   The OP asked about making accurate mixes.   I tried to help.   That's it.