Incubator forced air kit
Why would you even want to get an incubator forced air kit? A still air incubator will hatch eggs and it typically cost less. It is a fact, you can greatly increase your hatch rates by moving the air around.
Moving air creates a more even heat within the incubator. No hot or cold spots. Which is better for chick development. It also distributes the humidity more evenly.
Beyond an automatic egg turner, it is the next big upgrade you should consider if you have a styrofoam style incubator.
Cost
Adding a kit to the usual styrofoam incubator will set you back about $25. This one even comes with a candler (also known as a flashlight).
Forced Air Fan Kit for Incubators Hatching Eggs + Free Egg Candler
Or this one comes with a digital hydrometer for and additional charge:
Incubator Forced Air Fan Kit + Digital Thermometer/Hygrometer +Free Egg Candler
So why all the fuss?
Because I was able to do it for a fraction of that cost. If like me you have old computer cases laying around, that is really all you need.
What I did
DISCLAIMER: I am not an electrician and I do not recommend doing something like this unless you are say an electrician. This article is just telling the story of what I did, not recommending you do the same.
The 12-volt fans inside the computer case are exactly what I needed. It is basically what comes in the kit if you buy that instead. The power supply was a bit of overkill and honestly, since it was an old case it was also loud since it had its own cooling fan. I went on eBay and found a cheap power supply that had the right connector and specs for my fan. It was cheap because it was just enough to power the fan, nothing more.
Then it was the simple matter of mounting the fan inside the incubator, keeping it out of direct contact with the heating source and allowing for clearance of the egg turner. I took a piece of plastic and mounted the fan to it using for bolts with spacers to allow air flow behind it. Then a single longer bolt was used to mount it to the incubator lid. I used the single bolt because there was already a single centered hole in the lid I was able to fill.
Check out my post on Raising quail for eggs!