Passive Cooling methods that don't involve home renos

my growbox is getting rather hot i'm noticing after lining it with mylar to stop the light leaks, i have a fan inside my case which helps the temps alot and a few cups of water to increase the rh which also drops the temp a bit.

i was just wondering if you guys had any tips other that running an exhaust pipe out of the box because i don't want to be stuck either leaving the door open or damaging my rental property.

this is a legal grow so i'm not too worried about smell or all that, i was thinking some sort of cooler that the air runs through without leaving the box?

some ideas i had were:
- frozen lunchbag gel cooler thingies
- those little usb minifridges
- swapping out all the warm spectrum lights for leds

please help me cause right now i need more light but i will fry my plants if the box gets hotter, so i guess led light reccomendations etc. will be cool too.

check out and comment on my grow here!
https://www.rollitup.org/grow-journals/539855-romulan-x-mikado-mutant-purple.html

be the first! i'll appreciate it alot!

you could put trays of frozen stuff in front of your fan,or even open box, when light is on ? maybe connect the fan wae ducting to bring in colder air?

your box is wee innit ? is there no way to make it bigger? maybe mount the fan right on the side of the box? you know through like air con?

my box is about 6 feet tall and 3.5 feet wide so i guess its pretty small, it's also made of metal which might make a difference. thanks for the replies! i'll post some pics as soon as i get a chance my plants are much bigger now and the box is lined with mylar too!