Place the vanilla beans in your vessel of choice. Depending on the size of your jar, you may or may not need to cut the beans in half to fit.
Cover the vanilla beans with alcohol.
Allow the vanilla to infuse into the alcohol. Shake occasionally. You will know it's ready when the extract no longer smells like alcohol. This usually takes about four months.
Notes
Make sure to store it at room temperature out of direct sunlight.
You can reuse vanilla beans to make another batch of extract a few times. So don't just toss them as soon as you are done.
After you are done making vanilla extract, use those pods to make vanilla sugar! Give the pods time to dry completely, then place them into a glass jar of sugar and top with a lid. Give the sugar about two weeks to "steep" for best results.
Store in a cool, dark place. Homemade extracts will last a very long time due to the nature of the ingredients.