Yogurt adventures

We've had occasional plain yogurt shortages here, especially at the end of the month when grocery store shelves empty, so I'm trying to come up with a way of making it myself. As a healthy digestive system is the first line of defense against most things that attack the immune system, yogurt is our primary prophylactic. I'm keeping my eyes peeled for a yogurt maker but, in the meantime, I'm wondering how I might do it low-tech. Most online recipes involve using the stove at precise temperature and I'm not thinking our stove can handle that. Well, I got an idea today while bringing in the laundry. I've been using our Action Packers to bring laundry in and out, closing the lid when I fill it with dry stuff to bring in. Just before lunch, I put a few dry items in, shut it and brought it inside, promptly forgetting about it. Half an hour later, I remembered the dry laundry and went to fold it. When I opened the lid, a wave of heat came out. Aha! Yogurt maker! If I can heat the milk, cool it, add the starter and put the milk-filled glass jars (old peanut butter jars) in something like an Action Packer in the sun for the whole day, that should do it. Not an Action Packer itself though; they're too valuable in this neck of the woods to risk that kind of sun damage. We'll find a plastic container in one of the local China shops. Which do not sell, as one might think, china. Rather, they sell cheap mass-produced goods from China. China shops are all over the place here in Francistown.