I built this completely with materials found around my house.
This is NOT meant to cool down a whole room, it just creates a nice cool breeze.
Coleman Personal8 Cooler (or similar)
Small, cheap styrofoam cooler (usually under $10) will also work.
3 PVC elbow joints, about 1/2 in. ID (around $1 each at hardware store)
Drill with bit same size as OD of PVC elbows
Computer fan (about $5 from radioshack)
12v transformer* (not sure where to buy these...)
6 empty gatorade bottles
Duct tape (about $10 from radioshack)
Extension cord w/ switch (not totally necessary, but nice to have)
*transformer only necessary for a 12v fan, you can get a different one for different voltage fans of just install a plug if you have a 120v fan.
Step 1: Cut Hole for Fan
Put the fan up against the back of the cooler, mark with pencil around the outside of it, and cut out a square hole for the fan. Push the fan into the hole. A tight fit is good; it lets less air escape.
Step 2: Drill Holes in Lid of Cooler
With your drill, drill 3 holes in the lid for the pvc elbows. Insert the elbows in and secure then with duct tape.
Step 3: Gatorade Bottles
Fill empty gatorade bottles with water, and then freeze them. Once the water is frozen, remove them from the freezer and tape them together like a six-pack. You can modify this to compensate for different cooler sizes, my cooler just happened to fit them perfectly.
Step 4: Hook Up the Transformer to the Fan
Pretty self-explanatory... you can just twist the wires together or solder them if you are really committed.
Step 5: That's It! You're Done!
Put the frozen bottles into the cooler.
Turn on the fan and feel the cool breeze across your face...