Using a knife, slice the vanilla bean pods to expose the seeds
Add about 4 vanilla bean pods in each bottle
In two bottles, using a funnel add vodka
In the other two bottles add glycerine
Close the bottles and shake.
Store in a dark cabinet away from direct sunlight and shake the bottles at least once a week.
Vanilla extract will be ready to use from about 8 weeks, however the longer it matures the better.
Once in use, top up with more vodka or glycerine to keep the extract going