When building a reptile incubator there are several factors to be considered:
1) How many reptile eggs you plan to incubate at a time
Depending on the number of reptile eggs you plan to hatch you will need to increase the size of your reptile incubator. When you make the your reptile incubator larger you most often need to increase the heater wattage, fan circulation (if necessary), incubator wall insulation, and sometimes even a thermostat capable of handling the higher wattage heater.
2) Local temperature and humidity conditions
The main components in reptile hatching are humidity and temperature. The most ideal situation is to put your reptile incubator in a consistent temperature place in your house that does not get direct sunlight. The reasons for this is that reptile eggs are very easy to dry out & most thermostats have a harder time keeping a consistent temperature when the temperature outside the incubator fluctuates a lot.
If you live in a very dry climate you will want to make it easy to add water to your incubator and your reptile medium (when necessary). The dry air outside the reptile incubator will make it so you need to add water to your incubator more often. Also be very cautious not to make the incubator out of a material that absorbs water (like wood). The wood absorbs a lot of the humidity and makes it more difficult to keep the humidity level inside the incubator.
3) How Critical is it the incubator doesn't fail
If you are incubating very expensive or hard to find reptile eggs you will want to make sure that your incubator has extra safety precautions. For example if your heater, fan or thermostat were to go out during a hatch then you would most likely loose the eggs and have to start over. A possible solution is to use redundancy in your incubator design. A common way this is achieved is to install 2 of our IncuKit DC Thermostat, Heater, & Fan Combo Units in your incubator. The two units will run together and if one fails the other will make up the difference and keep the incubator running (You will want to test your incubator size and make sure that one IncuKit DC is enough power for your incubator)