I was surprised how easy it was. I used the rinse water from rice, and let it ferment until you can just start smelling that it’s fermenting. I mixed it into dairy milk with the cream still on top, and set it in a dark place for 4 days. Then strained the whey. The whole process took 7 days, with an outdoor temp around 73F.
Discussion
Sounds like it's well worth doing.
I'll probably have to wait until late fall where I am since I won't have temps back around 73 until then. (Sonoran desert)