DIY Yogurt

I've made my own yoghurt for years. Hugh Funny-Wittingball's recipe never fails. I use a regular big thermos rather than a warm place. I fill it with boiling water and seal before I start, which sterilises it and warms it up, then when the milk is at temperature, I empty it out and pour in the milk. Be warned, it takes very little time for 2 pints of milk to heat to 46C, but (seems like) forever to cool back down, so keep an eye on the thermometer.

https://www.rivercottage.net/recipes/radiator-yoghurt