I wanted to build a homemade incubator mostly to save on cost, but also for size, since I will be incubating a lot some day for a slaughter flock. My DH is an HVAC professional, and very handy, so he made the cabinet I had already lined with 2" thick Styrofoam into an incubator.
The box at the back contains two computer 12V fans, one that brings air in the bottom of the box (not outside air, but from within the incubator) and another that blows it back out the metal grate, which has heating elements behind it to heat the air up again. The wafer thermostat is inside the smaller box, with the controller sticking out the top for easy adjustment. The glass water pan is at the bottom, under the egg shelf, and fed by a tube running out the front of the box.
I have a viewing window at the front at the level of the eggs:
The eggs shelf is the entire area of the incubator (minus fan/heater box) and the chicks are protected from the heating box by a wall of hardware cloth. So far, total cost is $24 for the wafer thermostat from Amazon. Everything else were items we had laying around. The metal heater had been fried by water, so the thermostat was junk in it and had to be replaced. I am using a thermometer/hygrometer that shows lows and highs. The thermo stays around 95 for low and 104 for high. Spends most of it's time on 99-100. I know most would freak out about that temp range, but it resulted in 100% hatch, so I can't complain! An item we are going to add is a backup battery for if we lose power during incubation. It is also free and since it is for a computer, DH figures it should work. Hopefully, that will take care of power failures.
3/3/2017 I hatched 9 of 9 eggs set in the first hatch in this incubator. Those were the eggs in the picture above. They are two weeks old now, they popped out one after the other and were all healthy! I set 49 more on Feb 25th, 2017. They will be pure BO and some pure EE, some mix EE/BO. I was able to keep my humidity at 65% during lockdown on the first hatch by using a Tupperware container with a sponge. Without room for this on the egg shelf this time, I cut the front of the Styrofoam so I could remove one slat of wood and slide a sponge into the water pan below as needed during this next hatch. With a small Tupperware down below, humidity right now is about 20-25%. I will candle on Feb 4 to determine fertility.
3/6/17 Day 7 (on 3/04) candle of 49 eggs, 47 are definitely viable and growing, one is a maybe. Going to put a barricade up so I will know which ones are my 6 pure EE (came from a friend who only has EE) when they hatch. I also need to put some kind of extra shield in front of the heat source, the hardware cloth I have there gets REALLY HOT, so the chickies will need to be protected from that. I'm thinking a piece of 2" Styrofoam with a bunch of 1/2 inch holes drilled in it to let the heat still come through. Trying to use what I have!
3/22/2017 We had a 89% hatch rate from this incubator! 41 of 46 chicks hatched and had no deformities or problems hatching. No assisted hatching at all. I kept humidity 50-65%, and the chicks took care of the rest! Definitely a good idea for an incubator, but had some issues towards the end with keeping even temperature because it went on the fritz and DH had to disable part of the heating element assembly. But limped on til the end! He's going to work on a coolerbator for me next made from a double door mini cooler from work. But probably going to stick with a non-lightbulb setup.