Making 100% ethanol is easy to get if all you have is vodka, a still, a few extras and are ready to work for it.
I would distill the vodka to get 90%+ ethanol. Then I could get calcium hydroxide (aka hydrated lime) from
my local grow store or online and heat that to around 600C in a crucible (metal container) outside in a fire
to convert it to calcium oxide. Calcium oxide (aka quicklime) is then mixed in the nearly pure ethanol and let
to sit overnight. There it dehydrates the alcohol and converts back to hydrated lime. Distill the next day
using a drying tube to avoid moisture ruining everything and voila you should have 100% dry ethanol.
Make sure you store it right away with even a little calcium oxide in it.
Isn't chemistry fun?