Camping Gaz used to market a range of coolboxes etc and in very small sizes, as well as matching flasks......these were very high performing and one of their largest boxes could keep ice in it for a week if loaded as a block.
People forget that these boxes can be used as hot boxes for food....and in Egypt, there was a tremendous market for the small stuff as individuals could go around selling soup and drinks, as well as hot lunches..... No tricity needed of course.