I’ve tried making cider a couple times and my favorite is an informal approach inspired by the “Lifelong cider maker” anecdote in Sandor Katz’s Art of Fermentation:
I learned the crude technique at Quaker boarding school. Everyone there stuffed gallons of cider in clothes closets. Open jug, pour some out, leave lid raised on one side, then let it sit in the closet until it stopped bubbling.
In my case, I buy a 32 oz bottle of something I’d want to drink in any case, like North Coast’s organic gravenstein apple juice, and then leave it on the kitchen counter with cheesecloth over the top. If I can get fresh, organic apples or stone fruit, I’ll chop one up and throw it in hoping yeast from the orchard is riding along.
Bubbling starts after few days. Seeing it makes me happy, a bit of the natural world indoors. Consistent with an informal approach, and following Katz’s advice for spontaneous cider in Wild Fermentation, I like to drink it early and often, rather than trying to optimize and risking colonization by vinegar bacteria.
If mold grows on the froth, I scoop it off with a spoon, as we would with sauerkraut, and “rack” the juice through a strainer (to catch the froth) into another bottle, leaving the sediment behind.
I finish the bottle in a week or so and then start again :)