What you will need:
a stock pot
a lot of apples
a jelly bag, muslin, or a pillow case
maybe a little bit of sugar, but probably not
other flavorings as desired: ginger, cinnamon, etc.
In light of the apple harvest, I thought I might make some apple juice for Tambo's lunchbox. In the interest of not making life too difficult for myself, I decided to make straight-to-the-fridge apple juice, so that I wouldn't have to bust my hump sterilizing jars and whatnot. A stock pot's worth of apples made about 4 liters of juice, which I anticipate we will drink pretty quickly, hence the no-fuss methodology.
Somewhat foolishly, I didn't weigh the apples I used for this, though chopped they filled a large stock pot. I didn't bother peeling them--just chopped off the tops and bottoms, quartered them, and in they went. I added enough water to cover 3/4 of them, and let this burble away for about 45 minutes, then came at it with a potato masher. Once you've got a nice amount of wet pulp comes the fun/arduous part, depending on what sort of person you are, since it has to be strained through a jelly bag, helped along by you squeezing. Sterilize the jelly bag by pouring boiling water through it first; if you don't have a jelly bag a bit of muslin or a pillowcase, even, will do, though you have to find a way to rig it up (my jelly bag has ready-made loops, through which I stick large wooden spoons, suspending it over a pot via the use of carefully-placed chairs). Alternatively, you could sit it in a strainer over a pot, I suppose, and let it drip and squeeze.
So through the jelly bag went the pulp. I let it drip on its own while I did other things, but had to return to it to squeeze. This was like milking something. I squeezed and squeezed until I could get as much juice as I could out of the pulp, and was left with a beautiful, thick, cloudy liquid, which I returned to the first pot to heat while I added a really minimal amount of sugar to it (whether or not you need to add sugar will depend on what kind of apples you use, or what type of taste buds you have. For my 4 liters of juice, I only added about 3/4 of a cup of sugar. The usual admonitions apply: add a tiny bit of sugar, taste; tiny bit more; taste, etc. One can always add but not subtract, my friends.) While heating it you could add other things to it, maybe some slices of fresh ginger, or a bit of cinnamon--this batch was pure as the driven apple, though.
Out came the funnel, and into the bottles went the still-warm juice. I used bottles that I've had lying around, nothing fancy or new. If you were preserving this juice, all scrupulosity would apply, and new lids would have to be purchased, bottles sterilized, heat treatment, etc etc. Our fridge juice though, Bob's your uncle.