Use one Quart size bag.
place 1/2 cup of milk in the Quart size bag.
Place 1/2 cup of whipping cream in the Quart size bag.
Add 1/4 teaspoon of your favorite flavor.
Add 1/4 cup of sugar to the Quart size bag.
Grab one Gallon size bag.
Place 4 cups (minimum) of ice in the Gallon size bag. Add the 3/4 cups of Rock Salt too.
Place the quart size bag in the gallon size bag and shake until your ice cream is the consistency of a frosty. Eat and enjoy!