What can I put in y hamsters cage to cool him down?

well you can place a fan in near the cage i have had countless hamsters and i am a vet tech. also you can place a little house like a rock one typically used for reptile and that will keep a cooler temp inside of that cage..place a piece of paper-towel in there and he or she will use that to insulate the house that will also cool the temp. make sure you keep the water supply up and put a little in a bowl and put in it there if he or she gets to hot they will go in there to cool off..