How to make your own Fermentation Lock (Not a balloon!)

Step 3: Results

There you have it! You now have your own homemade airlock and it cost you less than $2. Be proud of yourself.

Also, I recommend using water or vodka in your airlock, not sanitizer. This is what I found about it on wikipedia.org (the greatest site ever!).

"Many brewers simply fill the liquid chamber with water, which in itself acts as a sufficient barrier to contamination. Others use a sanitizing solution in their airlocks. However, this is generally a bad idea with a small airlock. Sanitizer does not offer much, if any, additional protection, since airborne bacteria or wild yeasts are unlikely to be able to pass through any liquid and become airborne again in sufficient quantity to spoil beer. More importantly, under some circumstances, material from the airlock can be sucked into the fermenter, and even unboiled tap water is better for your wort or must than most sanitizers. As a compromise, some brewers use vodka, which is sanitary but will not contribute any flavor or character to the finished product other than a small amount of alcohol."