Incubator basics

• An incubator is nothing more than a draft-free box designed to keep eggs at a constant temperature and humidity. Most homemade incubator designs, and some small commercial units, rely on light bulbs to generate heat. Humidity is provided by a shallow pan of water with a sponge partially exposed to the air to act as a wick.
  Vents to allow fresh air into the box are located to minimize drafts on the floor of the incubator.
  
  

Temperature control strategies

• If the incubator is to be placed in a location with little variance in ambient temperature, adjustable vents can be used to regulate the temperature inside the incubator. Leaving the heat source constantly on and allowing excess heat to escape through the vents eliminates the need for a thermostat. Once the vents are calibrated, the temperature inside the incubator should remain constant.
  The use of a thermostat reduces the possibility of failure due to wide swings in room temperature. If you are hatching a large brood, it will be worth the extra effort to wire a thermostat into your heating circuit. A small circulating fan also might be a good idea. Still-air incubators have been around for a long time and provide good results. Circulating warm air inside the incubator reduces hot or cold spots.
  
  

Materials

• An incubator can be built out of a wide variety of materials. Cardboard boxes, foam ice-chests, plywood, even old refrigerators make suitable incubator enclosures. As long as the enclosure can be vented and air leakage controlled, you can probably use it for an incubator.
  
  

Simple plan

• The simplest way to construct an incubator is to start with a large foam ice chest. Place two ventilation holes 1 1/2 inches in diameter on each end, six inches above the bottom of the chest.
  
  Place a 1 1/2-inch hole in the middle of the back of the chest, 10 inches from the bottom. Place a piece of 1-inch PVC pipe through this hole. Allow 2 inches of the pipe to protrude into the box.
  
  Thread the cord of a lamp socket with a 25-watt bulb through the PVC tube. The light bulb will be your heat source. Do not allow it to come directly into contact with foam surfaces.
  
  Plug the light in and allow it to operate for four hours. If temperature is too high, increase size of ventilation holes.
  
  While primitive, with the addition of a pan of water and a thermometer, this box will act as an incubator. Detailed plans of better and more advanced models are available through the links below.