I found the Rush Lane Poultry videos a couple of years ago and built one of his designs using an old plastic cooler with a GQF wafer thermostat and an old computer fan. It was inexpensive, simple to build and works great! I have only one regret...I should have installed two light bulbs in case one burns out, as was recommended. I was so sure that if I installed a new bulb with each hatch, that it wouldn't be an issue. It has worked out great until today...I woke up this morning to find the light bulb burned out (yes, it was a brand new bulb) and the temp had dropped to 76 degrees! My quail eggs are on Day 9 and were developing nicely when I candled them yesterday. So now I get to sit on "pins and needles" until Hatch Day to see if at least a few survived. :-( As soon as this hatch is done, I'm modifying my incubator with a second lower-watt bulb to ensure I don't have to go through this again. Good luck building your own incubator, nayeli, I agree with Fred's Hens, you can't go wrong with the Rush Lane Poultry videos!
Easy fix. I wish I had as well, but $2.48 at Lowe's or Home Depot and Ta Da !!!! One fixture becomes two.