Cut the vanilla beans open so you can see inside. Use a knife to run down the middle of your beans and chop the beans into small pieces. Add the beans to your mason jar.
Once you've chosen your choice of alcohol, pour it on top of your beans and shake well.
Keep in a cool, dry place. Be sure to shake at least once a week. And ensure wait at least 8 weeks before using. The longer you leave it, the more intense the vanilla flavor will be.
If you haven't opened the jar since making the extract, this vanilla extract will last for years! Add fresh beans, and additional alcohol if you're not finding the flavor as strong as you'd like.