A still separates alcohol from water, resulting in a highly alcoholic product. Alcoholic spirits such as vodka, tequila and moonshine are created using stills. There are many DIY still designs, including one made from a 5 gallon bucket.
Warning: In many countries, homemade stills are illegal. Check your local regulations before taking on this project. Stills can also be dangerous. This website or its creator accept no legal liability for the improper or illegal use of this design.
The 5 gallon bucket still uses 2 buckets, one nested inside the other. The inner bucket holds the initial low-alcohol liquid and is heated to the boiling point of the alcohol by use of an immersion heater like this one.
The alcohol evaporates and condenses on the top and side of the bucket. It collects in the bottom chamber where it is harvested.
Some amateur brewers use simple stills like this one to produce fuel for their gasoline cars, which is legal if properly licensed. The best resource I know of for producing your own ethanol for fuel is www.iMakeMyGas.com.
The full instructions for making the 5 gallon bucket still can be found on Prepper Ideas.