If you have access to a lot of free apples, you can easily make cider from them. Any apples will do, but they should be as ripe as possible. This instructable shows you a simple method that does not require any special equipment.
Update Oct 2014 - In response to popular demand, I have just published an extra Instructable about how to make the press in step 4. Just wood, a few plastic containers and a car jack - cheap but very effective :)
Step 1: Collecting your apples
The first thing is to get some apples. You will need quite a lot of large containers, because you need to collect about 4 to 5 times the volume of apples compared to the volume of juice you want to make into cider. The container shown here is a 5 gallon (22 litre) fermentation bin.
A sheet or blanket is also handy. Put your sheet under the tree, climb up the tree and shake it. Lots fall off. The advantage of this method is that generally the ripest apples tend to fall off, and seriously under-ripe apples stay on. When you put them into the bucket, pick the apples up by hand, so you don't get all the twigs, leaves, earwigs etc.
Step 2: Containers for apples
Step 3: Pulping the apples
Step 4: Building a simple press
Step 5: Preparing the apple pulp
Step 6: Pressing using a car jack
Step 7: Sterilising the juice
Do not add your yeast for about 24 hours after sterilisation or it may be killed as well!
Step 8: Add yeast
Step 9: Checking acidityAfter a week or so, the yeast in your cider will have turned all the sugar into alcohol. At this point you can check to see how sour the apples were. If the apples were not completely ripe, or you only had wild apples the juice can be very sharp. This can be so sharp you can't drink it. You can make this less so by adding calcium carbonate (aka precipitated chalk). This will react with the acids in your cider and neutralise them. You may need to add several ounces per gallon, but do this in stages because when you add it, the reaction of acid and carbonate will release carbon dioxide, so it will fizz.
Step 10: Bottling
After you have left your cider for a few weeks, it will clear as the yeast settles, and it will be ready for bottling. It may not be completely clear, but that doesn't really matter because it can clear in the bottle.
For each wine size bottle, you will need to prime the bottles by adding just over half a teaspoon of sugar to each. This will restart the fermentation, but because it happens in a sealed bottle, the carbon dioxide released gets dissolved into the cider and creates pressure. When the bottle is opened later, the pressure is released, allowing the gas to esacpe, which creates the sparkle.
You should use bottle designed to stand pressure such as bottles made for sparkling wine. Seal your bottles with corks and champagne wire cages. You can use beer bottles with crown corks, but this needs a special tool.