You can make yogurt without a machine. Heat 2 gal.milk hot enough to kill bacteria, 180 to 200 F, hold it at that temp for 5 to 10 minutes. bring the temperature down to very warm 110F. Mix in a couple spoonfuls of plain yogurt from the store. Put it into cups or half-pint clean canning jars with lids and set in a pan of very warm water and cover it. Keep the water very warm set in oven with the light on, leave it for 4 to 6 hours Do not disturb or jiggle. and the yogurt will thicken. Refrigerate overnight. Keep in the fridge. Mom often made yogurt. You can add plain gelatin for a more solid yogurt.