12v computer cooling fan is sufficient to circulate the air .. 12 volt supply from an old computer mounted externally .. cheap as chips to run .. hook the supply into the mains and leave it on all the time the warming cab is in use. If you have a fridge freezer as the warming cabinet consider turning the smaller part into a food dessicator/dehydrator... dried strawberries, bananas, apples, raspberries - all yummy in your own breakfast muesli ! ... or really go to town ...home made Biltong !
You have all the kit available - might need a slightly higher wattage heat soiurce for the dessicator.