Use kitchen scissors or a sharp paring knife to cut each vanilla bean in half, then lengthwise down each bean, opening them up.
Put vanilla beans in a glass jar or bottle with a tight fitting cap. Cover completely with the vodka.
Give the bottle a good shake every once in a while. Store in a cool, dark cabinet.
This lasts for years. You can keep topping it off with vodka once in a while as you use it, just remember to give it a good shake. Eventually, add some fresh vanilla beans.