I'd read of a "farmers" method that makes a potent mix in very little time, but the sake remains white, the taste is supposed to be very harsh, with a high alcohol content... one of these days.
the koji used to make sake (the rice doped with yeast) can be mixed with water and salt, you let the stuff sit until the rice gets very soft, and can use it in lots of different recipes. it's a great meat tenderizer/marinade.
It turned out OK but not so great that I would do it again instead of just going and buying it. Plus I don't drink it that often so 11 litres hangs around for a long time.
The biggest turn-off for me was I made it in a closet so I could control the temperature and everything in there smelled like fungus for months after.
I did the whole lactic starter and letting it clear too. But again, the end result didn't justify the time investment.