You can make a cheap paint by mixing milk with slaked lime. The milk should be fermented to make it acidic so that it turns acidic so as to react with sour milk to make salt which is the paint. You can add vinegar to the mixture to preserve it. It looks trashy on applying the first coat but after drying produces an excellent matt finish.
This method of producing a homemade paint you described looks simple and direct. I am looking at the economic gain, I doubt if this will be of economic advantage compare to buying from the market. Milk is not cheap, getting some liters of milk to do this may cost a lot of money.
This custom made paint formula is straightforward, non-harmful, and it costs alongside nothing to make. Also it's entirely remunerating to make your own particular workmanship materials. Remember that this paint is ideal for investigating the way toward painting, however it's not awesome for making a perfect work of art to hang over the mantle. Basically, it's not a gum based paint or acrylic paint substitution!