YOgurt maker?? it is so easy
just bring milk to a boil(make sure to scrap the bottom so that it doesn't burn)

let cool till it is cool enough to say Hare Krishna Hare Krishna Krishna Krishna Hare Hare
Hare Rama Hare Rama Rama Rama Hare Hare once while placing a clean finger in the milk. not too cool, just one mantras worth

then add yogurt with live culture, a good one that is not too sour like brown cow

then let sit in a warm place like a low oven for 12+

test if you like the consistency

longer you wait thicker it gets but also too long makes too sour

then put in fridge and your done

dont forget to save a cup of your new yogurt for your next batch

i put one cup of yogurt for about a gallon of milk. simplier than pie.

Also, yogurt makers are in many thrift stores- it's one of those failed-marketing gadgets from the 1970's. They generally consume little power and work well. They dont tend to be automated (meaning you still have to remember to turn them off after heating for the incubation period). I used the kind that makes little cups of yogurt, and have seen those for $2-3 quite often. If they are missing the cups you can use half-pint mason jars.

I do mine in quart jars in the dehydrator set at around 90 degrees.

The simplest recipe I have is taking a gallon of milk ( I use full fat, whole, organic... never tried skim but if you like to experiment, might be worth the try), bring it to a low boil (my gran called this 'scorching') and let it sit someplace where it can cool to the point where you can keep your little finger in it without going "Youch!"

a thin skin will form on the top, I try to keep this and mix it in after the whole batch sat overnight.

take some left-over yoghurt that you bought from the store (again I use full, whole milk yoghurt with live cultures) and mix in a little of your scorched milk to make it runny. Then add, carefully, slowly, so not to disturb the skin too much, to the lukewarm gallon (less the little bit you just took out) of milk.

cover lightly with cheesecloth/saranwrap and place over night in the oven or in a warmish spot. The pilot light in the oven provides just enough warmth.

the next morning it has curdled and that's kinda how I like it: runny enough to make smoothies etc. Store in the fridge, flavour to your heart's content.

blessings

I make Viili yogurt which requires no equipment at all. just add a couple of tablespoons from your previous batch to no more than 2 cups of milk and let it sit at room temperature for 24 hours and that's all there is to it. I got my starter culture from my mom who has been making it for a little while now but I believe she got her starter from this site
fermentedtreasures.com/yogurt.html#item2