I have made this phone cooler that can be attached to your phone with MagSafe magnets. First, you just need to fill this MagSafe cooler with some water and put it to your fridge. Wait for some time till the water freezes Now, If your phone gets hot, you just gotta attach a frozen MagSafe holder to cool your phone down. If you print more than one MagSafe cooler, you can use one after another so you can continue on your phone without a pause.

I bought this MagSafe ring: https://sl.aliexpress.ru/p?key=MuTmsuQ Please make sure you also get the one with the same dimensions.

If water leaks from the cap screw, you can apply some glue.