Two main differences that jump out to me are coolers seal and the amount of product. A 1/4 full humidor of any type will do what you want as easy as a 50-75% full one. The humidity in air will fluctuate easier than humidity in cigars/cedar. You may want to open the drain plug at the bottom of the cooler. Humidity will tend to be higher at the bottom. Open that drain up and you will have a slight bit of air flow and may drop the interior humidity ever so slightly without having to worry about vast fluctuations.