BUILD INSTRUCTIONS:
Full credit to FigJam for adapting this original playa-tested design to the small 5 gal. form factor.
Full text instructions:
1) Buy the stuff
2) Add 2 gallons of water to the bucket to establish a high water mark. Use a sharpie to draw a line around the outside. (I drew one line at 1 gal, and another at 2. It made me happy.) Keeping about 1" above that fill line, and below the top reinforcement ring that's about 2" below the top, drill as many holes into the bucket as you reasonably can. The photo shows this being done using a 2" hole drill bit. I didnt have a 2 inch bit, I used a 1.5 inch bit. It really doesnt matter, you just need holes to allow air to pass through, while still leaving it structurally viable!
3) Cut the shade cloth to a 13" x 6' strip with scissors. This will roll up in a tube, covering the inside of the bucket and acting as an air filter. The 6' length will give you, essentially, a double-layer filter inside.
4) Cut the swamp cooler pad with scissors to 13" x 30". Coil it inside the bucket, and trim as needed to it fits nicely. You'll want to cut a slight wedge off one side since the bucket is a little smaller at the bottom than at the top. About 1" off at the bottom, angled towards the top edge, should give it just the right slight cone shape.
5) Cut about 4' of irrigation tubing off to work with. Cuts pretty easily by slicing as if it were cheese, using a simple box cutter. Use the T-coupler to make a coil that just fits inside the top of the bucket, about 1" down from the edge of the top. The rest of the 4' section will go from the center exit of the T-coupler toward the bottom of the bucket... it should slide right over the output of the fountain pump.
6) Put the fountain in the bottom of the bucket and make sure the tube leading down from the irrigation tube ring is the right length. Trim as needed. Route the power cable for the fountain behind the shade cloth and out one of the big air holes we drilled in step 2.
7) Using a small drill bit (1/16" is about right), drill holes roughly every 2" in the bottom of the irrigation tube ring (no need for precision, it doesn't matter). This will allow water to squirt down onto the cooler pad, keeping it wet, so the evaporation take place properly. NOT the tube going down to the pump, of course, just the ring itself.
Now we turn to the computer fans. Place a fan on the bucket lid, right against the edge but inside the top "ring"/ridge around the edge. You do need to be right against the edge or you won't be able to fit both fans side-by-side across the lid. Using a small drill bit or even a thin pen, mark the four holes at each corner of the fan. Use a drill bit that fits comfortably inside the fan's mounting holes to drill starter holes. (Not too big, not too small) I think I used a 1/8" drill bit. I didn't even use a drill, the plastic is very soft. By starting the holes with a 1/16" bit, I easily hand-twisted the bit right through the plastic, checked with the fan to make sure everything lined up right on all four holes, then enlarged the holes with the bigger drill bit, again, just by twisting the bare bit in the hole, by hand.
9) Now we cut the hole in the lid for the fan. Hold the fan in place so you can see the holes are in the right place. Take a pen or sharpie and draw a rough square, well-inside the fan's circular fan part. Make sure it's not too big and you have plenty of "corner" left for the screw holes to stay in place. Now take a standard box cutter knife (Stanley utility knife) and just cut the soft plastic square out. Check with the fan placement again, and using the knife, carefully enlarge the hole by carving out the soft plastic until you have a hole just big enough to have a clear air passage, and still have plenty of plastic at the corners to hold the fan. Be especially careful along the edge that's in the middle of the lid... you need an intact strip of plastic between the two fans to keep the lid structurally strong.
10) Once you've cut the hole and you're happy with it, mount the fan into the lid. (The fans come with screw for this) They screw from the bottom of the lid into the lower corner hole of the fan.
11) Repeat for fan #2. If you want a second fan, just be sure there is a space between fans to keep the lid structurally strong. When I made mine, I did not opt for a second fan. I bought a desk fan that plugs into the wall and removed its first basket, then screwed the basket cover to the lid using nylon wire clamps. They are little strips of nylon that have a hole to put a tiny screw into. I used this and tiny screws and nuts and then.. because I can... superglued the screws and nuts and fan case to the Home Depot bucket lid.
12) Add 2 gallons of water, connect the fans and pump to power and watch it go! Make sure there are no leaks. You may want a planter dish from a nursery to catch any drippings from the bucket. Fine-tune the position of the holes drilled into the poly irrigation line if needed... it shouldn't be a big deal to cut a new ring if needed, the stuff is cheap after all, and coming in 50' quantities, you have lots!
13). Attach with silicon sealant, or get creative! (Photos of some ideas to come)
14) Enjoy! Remember, swamp coolers are only effective in climates with very low humidity. Because I live in Las Vegas... super desert... I have a constant struggle with low humidity.
If you have any questions, feel free to drop me a line.