Basically, you cut a hole in the styrofoam top to attach the dryer tube and another hole in the top that will fit the desk fan without it falling through. Insert pom poms into the tube. (Why? We don’t know.) Dump a bag of ice in the cooler. Add beer if you want. (So far this is the only suggestion Maximum DIY stands behind!) Cover, turn on the fan, and prepare to have the few inches of skin near the vent cooled marginally. If that.
A science-type commenter calculated that a cheap window unit will “cool you 9 times more in just one hour than your bag of ice can do over any amount of time” and cost you only 6 cents. He points out that to match the cooling power, you’d need 9 bags of ice at a cost of almost $19 for that same hour.
But another commenter called science guy a killjoy for all the people who rent and can’t put in a window A/C (she’s got a strict landlord, huh?).
Another commenter said it works ok and you can ditch the tube. (But then where will you put the pom poms? No rude replies, please; they’re not our idea!) He added it would work great in a tent. Good to know.
If you really are hellbent on making your own homemade air conditioner, you can find instructions for a more expensive, more unwieldy, but more effective diy A/C at Geoff Milburn’s site.
But even he admits: “I realise small air conditioners are quite cheap. But then you don’t get to build anything!”