Materials list:

28 QT. cooler (can get from attic or garage sale )Can use any size you want or have.
4-5 ft. hardware cloth
1 - old lamp with cord(attic or garage sale)
1 - old CPU fan
1 - 12volt transformer(scavenged from old answering machine, telephone, chargers, etc. I have tons of these things in a drawer from various old appliances) or you can buy one at radio shack.
1 - electric water heater thermostat (single pole)
1 - old picture frame with glass/Plexiglas ( or buy for $1 at Dollar Store)
1 - thermometer that shows temp and humidity. (can find at most Big Box stores and online for under $10)
1 - old dish
2 - old prescription pill bottles with lids.
6 - self taping screws
1 - roll electrical tape
1 -1 tube caulk(silicone )

I cut and bent the hardware cloth to make a rack that fit into the cooler. Cut off any extra and remember this stuff is sharp wear gloves! I used the cut off piece to block off the area I was putting the light and the fan to keep little nosey chicks from getting hurt.

The thermostat is a single pole I found in an old water heater I had in the barn. It had a temp. range from 90-150F, using a screw turn to increase/decrease the temperature . The screw at the top is numbered #1 and the lower is #2. If you don’t have an old water heater lying around you can get one from Lowes or Home Depot for about $8-$12.
(thanks to MissPrissy)

I used an old lamp and removed all the old stuff except the brass bulb holder. It has a switch in this piece that slides back and forth but it is not necessary . I measured the old bulb holder and drilled a hole in the side of the cooler that the socket would slide into tightly. I used silicone to hold it in place. I took and old aluminum loaf pan and cut a hole in it slide the light bulb around it and glued the pan on the inside wall of the cooler(used for a heat sink).

I am not an electrician so the next part may not make any sense .

I drilled a second SMALL hole on the side of the cooler about 4 inches from the top to thread wire in to the thermostat which will be placed on the INSIDE of the cooler and held into place after wiring using 2 self tapping screws.

I connected the ribbed wire to the silver screw on the lamp then I used an extra 5“-6” inch piece of wire from the lamp cord to attach the brass screw on the lamp to the thermostat #2 screw, then used the non ribbed wire of the cord to wire it to the #1 thermostat screw. All that wire is on the outside of the cooler. I then tested it to make sure the thermostat would turn on my light. Then I silicone all holes that the wiring went through.

Above the light I drilled a hole big enough to run the 12v power adapter wire through after cutting the end off. I tied a knot in the wire to keep it from pulling through and mounted my PC fan using 4 self taping screws. I wired the black to the black and the red to the black with white striped wire.

Using a drill bit the a little smaller than the prescription bottles I drilled 2 holes on each side of the other end of the cooler, about 4” or so from the top of the cooler. I used a sharp kitchen knife to cut the bottoms of both prescription bottles off and to whittle the holes to the size so the bottles would fit tightly into the two holes. I then pushed the cut off ends through the holes and silicone those into place. These will be vents that you can open by removing the cap to adjust the humidity.

Next remove the picture frame and discard keeping the glass. Place on the top of the cooler on the OPPOSITE side from the fan/light and trace the glass. Then using a ruler measure a square INSIDE the glass outline about 1” . Take the sharp knife, BE CAREFUL, and cut out the INSIDE square(if your cooler is as hard as mine was I used a small dremel) . Set the glass on the new lip you created and silicone it in place.

Place an old dish that will fit on the light side of the cooler half filled with water. And turn on your incubator.

Adjust the Thermostat until you can keep it between 98F-101.5F. 99.5 is supposed to be the perfect temperature. Maintain that temperature for about 2 days before you start.

Humidity is a big debate in the forums and all I can say is I kept mine between 40-50% humidity until the last day and then turned it up to 60-70% all day till they hatched. This is my first hatch and I had 100% hatch. 8 out of 8 !

I am posting a video so you can see my homemade incubator and maybe that along with the explanation will help anyone who wants to try it! It was a lot of fun!
***Note: the green egg you see in the video is optional. It shows the temperature INSIDE the eggs.

1 - large plastic Easter egg
Hair gel
1 - digital MEAT THERMOMETER( I got mine from Wal-Mart)

Cut a hole in top of LARGE Easter egg big enough to fit meat probe through. Tape egg together fill egg through hole you cut with hair gel . Insert meat robe into CENTER of egg and hot glue in place.​