This seems simple enough to put together even for us less handy types.
There is a frozen gallon of water in the center of the unit, comprised of a bucket and a liner. A fan blows the cold air through three holes.
Now if only that styrofoam liner could be made of recycled styrofoam...
Here is what you need: a plastic 5 gallon bucket, styrofoam liner, pvc pipe, small fan, and ice.
"Desert Sun" who created this design says that one frozen gallon jug of water lasted six hours. The temperature in his house was 84F, and the cooled air was in the mid. 40F range.