I bought a yogurt maker from Julian Graves, the nut shop. Brand is "Easiyo". It's a 1 litre plastic container in to which I pour a pint pot of UK double cream, the rest of the volume I fill with some milk to provide lactose for the bacteria and water to keep it fluid for pouring. About 50:50. The yogurt maker itself is a plastic insulated flask which has an internal shelf and a mark. You fill it to the mark with boiling water, put in the yogurt fermenting container, which then sits on the shelf, pop the lid on and wait. I decant it in to fully waterproof sealable food beakers after three days. Shake it first. I leave it at room temperature. I have a production line but mostly it gets eaten within 7 days. I use Total brand Greek yogurt as my starter culture. It will do about six batches before becoming contaminated and starting to produce alcohol. My kitchen is loaded with a yeast since I tried some lactofermenting of rye flour, to see if I could tolerated home fermented sourdough rye bread. I can't. But it was nice trying.
You get a layer of cheese inside the top of the lid and around the top of the yogurt container screw thread. I clean this off with a tissue and scald the lid with boiling water between batches. I don't clean out the container as this is the source of bugs for the next batch. Until a yeast gets in that is, then it's a re-start after a mega sterilisation.
I like the taste, my wife doesn't. I guess it's acquired and I have the driving need for calories. Access to raw dairy is quite difficult in the UK (though far from impossible) and fermenting the cream appears to un-pasteurise it.