The first thing you will want to do is open your small, pint size plastic baggy. Next you will want to combine your sugar with the half and half and vanilla all in the plastic bag. Once everything is in the baggy, make sure it is closed and sealed tight.
Afterwards, you will need to get the gallon size bag ready. Open your gallon Ziploc bag and fill it about half full with ice. Once the ice is in the baggy, add the half cup of salt right into the gallon bag, over the ice. Before you close your bag, place the sealed, pint size bag in along with the salt and ice. When the pint size bag has been placed into the gallon size, seal the gallon size back tight.
After everything is combined into the right baggies and they are sealed tight, it is time to shake. It should take about five minutes or so of continuous shaking to start seeing the difference of the liquid turning into the solid. You want to shake the gallon size bag really well until you can feel the mixture of things in the pint size bag starting to get ice cream