I have a small, soft sided, “six pack” cooler. Currently only has two beers in it. I think the brand is Polar Bear? I find it’s pretty efficient. Helps if you keep it pretty full. If not, you have to keep it full of ice. When necessary I buy a bag of ice at a grocery store or gas station. More often I just get a cup of ice from anywhere selling fountain drinks. Costs less and wastes less. Still need to add ice daily, but that’s generally not a problem.