Combine ingredients in a clean 1 lb coffee can with a tight fitting plastic lid. Tape lid for added security. Place 1 lb coffee can in 3 lb coffee can. Pack crushed ice around the smaller can. Pour almost 1 cup of rock salt over the ice. Replace lid on 3 lb can. Roll the can back and forth on the floor or sidewalk for 10 minutes. Remove the inside can carefully. Keep salt solution out of the small can. Remove lid of small can and stir ice cream with a rubber spatula. Replace and retape lid. Drain ice water from larger can and place smaller can inside. Repack with ice and salt. Roll back and forth 5 - 10 minutes more depending on how firm you like your ice cream. Makes about 3 cups.