Use a sharp knife to split the vanilla beans in half lengthwise, leaving one end attached.
Place vanilla beans in glass jar or bottle. Use 5 beans per 8 oz of vodka. Cover the beans with vodka, and store in a dark place, giving the bottle a shake every week or so.
Let the vanilla extract sit for at least 8 weeks before using. At that point, you can remove the beans if you wish, or you can just keep adding more vodka as you are using it. You just want the beans to stay submerged in the vodka.
Using different types of vanilla beans will give you a different flavour vanilla extract. Mexican vanilla beans will give you a bold and smokey flavour. Madagascar beans will produce a rich and creamy vanilla, while Tahitian beans will give you a floral aroma with a chocolate-cherry undertone. Bourbon beans will give your vanilla extract a nutty-chocolate character. You can even use a variety of beans to give your vanilla extract a unique flavour.
Recipe by Faithfully Gluten Free at http://www.faithfullyglutenfree.com/2013/09/homemade-vanilla-extract.html