Here is our instructable for a very inexpensive and very quick portable A/C made out of a Styrofoam cooler. I did this project with my 4 year old daughter after we had seen some of the other home-made Air Condition (A/C) units and she asked it we could make one. The challenge we put forth though, was to try to make it with whatever tools and materials we had lying around the house and garage.

Step 1: Tools and Materials

Materials

1 x Inexpensive Styrofoam cooler (we got ours as the dollar store where you can actually get things for a dollar :) )
Duct Tape
1 x 15 inch piece of 3/4 inch PVC pipe (we had some as scrap around the garage)
1 x Inexpensive high speed fan. We had a Honeywell TurboForce Fan.

Tools

1 Dremel Rotary Tool (we used the Dremel 4000)
1 Cutting Disk for the Dremel (we used the thin cutter)
Scissors
A marking pen (i.e. Sharpie)
Safety glasses
Tape Measure

Step 2: Taping and Cut the Cooler for the Venting Holes

On the cooler, locate where you would want the venting holes to reside. For us, we did this just where the flat part of the cooler started. Once you have this, now place a single length of duct tape across that side and location.

Now, take a section of 3/4" PVC pipe and trace 3 holes in roughly equal distance from each other, on the tape.

Take the Dremel and put on the cutting bit and then grab your trusty safety glasses. Very slowly, and very carefully, cut the hole out. If you don't feel comfortable with the cutting bit, try changing to the routing bit and doing a freehand cut. The way we cut it was to make a single cut down the middle, then make another cut perpendicular to that one. It formed an cross to which we were then able to make quick cuts to remove the rest of the hole. Don't get too hung up on the hole being just right, in fact you want it to be a little smaller than your drawn circle. If you do that, it'll create a nice snug fit for the PVC pipe.

Step 3: Fit and Cut the PVC

With your newly cut holes, feel free to test them with the PVC, hopefully they are nice and snug. If not, don't worry too much, you can place them and then follow up with smaller strips of duct tape to keep them in place and get a better seal.

Take your PVC pipe and measure 5 inches, then mark it off with your marker pen. Now take the Dremel (don't forget your safety glasses!) and cut the PVC at that mark. Do this part 2 more times so you have 3 total PVC pipes of roughly 5 inches in size.

Step 4: Time to Cut the Lid

Take the lid of the cooler and place the fan on top of it. Make sure to place it so that the fan, if on, would be blowing down into the top of the cooler lid. Mark the lid with your marker pen to note the size of the fan in relation to the lid.

Now that you have an idea of where it will be, you need to duct tape of this part. Make sure to place the tape in strips covering everywhere your marked area would cover. We are doing this for 2 reasons. The first being that the duct tape will add a little structural support when we are making the cuts. Styrofoam is not the most robust of materials and can break off in unwanted ways :) The second reason is that it's helping to give the cuts a little better of an edge to work with, especially when we want to go seal the pieces when we put everything together.

Once you have the duct tape down, you need to place the fan once again and mark the lid with your marker pen to note the size of the fan in relation to the lid.

Now that you have the marking, put on your safety glasses and cut the lid. Remember to go nice and slow.

Once you have the opening, place the fan on it. If you need to trim up some cuts, go ahead and do so. Just be careful not to cut too much out. You want a nice snug fit for the fan to sit on and blow down into.

Step 5: Put It All Together

Time to put it all together!

Take the PVC pipes and place them into their holes. Take small cuts of duct tape and form a seal around each of the PVC next to the cooler.

Take the fan, place it on top, and then duct tape it down and form a seal to the lid as best as you can. We're not going for engineering marvel here, we're aiming to have it sit in place and try to avoid losing as much of the pressure as we can when the fan blows into the cooler.

Go ahead, use that duct tape wherever you need to. As Red Green would say, Duct Tape Forever!

Step 6: All Done, Just Add Ice

That's it, you're all done. Now you just need to add ice to the cooler and turn it on. Better yet, add your favorite drinks and ice, and have that cooler work dual purpose while you work in your garage, or out on your patio, or even in a room where you just want a little more cooling action added.

Simple, easy to do, and very inexpensive. My daughter loved how quick we were able to do this, and we've already started talking about what we can do to make it better, but while trying to keep it inexpensive and easy.