I posted this very simple method previously on another forum. So called "descending hear" method. Equipment needed: a heavy, lidded pot; small (1/2 cup) containers; blanket or equivalent.
Water is set to boil in a heavy lidded pot, like enameled iron or similar. Milk is brought to a simmer and left to cool until you can hold your finger in it for 10 seconds. Add a spoonful of commercial yogurt to the milk and mix well. Empty water from pot and place small jars in it. Fill jars. Replace pot lid. Place pot on a folded blanket and wrap snugly. Leave until it has cooled to room temp. We left it overnight. The yogurt will be somewhat creamy but will set up more as it cools more in the refrigerator.
I used whole organic milk (1 qt) and organic plain yogurt (1 teaspoon). DELICIOUS product. Stupid easy. The hardest part is folding up and putting away the blanket or comforter.
It was suggested that this was the troglodyte method and indeed it is! No special equipment or long power input necessary.
ETA, one teaspoon of yogurt is all that is necessary for a quart o milk.
