How to make mini incubator

My brother raises Bangkok chicken at backyard. He has two hens that was laying some eggs. Each hen lays 13 eggs in a clutch. A hen hatch 13 eggs but it eat three eggs. I think the chicken know that it is impossible to hatch more than 10 eggs. Other chicken does not go broody, it let the eggs. It is unusual for Bangkok chicken. Most Bangkok Chicken goes broody.
I have an idea to create a mini incubator chicken to hatch the thirteenth eggs. In my country, we are difficult to buy mini incubator because there is no pet shop that sell mini incubator.
Before make incubator you should provide wood, lamp, rack, water tray, thermometer and other. You also need tools like saw, hammer, burdizzo, and other tools.
Before creating the incubator, you are better to draw the design.

Here are the steps of making mini incubator:

1. Create a wooden box 60x60x60 cm. Create the frame of the box first and The front side is glass, so you can see the progress of hatching. Nail to cover the frame with triplex or wood. Notice: some wood contain chemist that is very dangerous to embryo. The poison often fails the egg hatch.
2. Put the tray at the middle box. You can make tray with fence or you can use the wire try. Do not use plastic tray because it will not good for the eggs.  
3. You can put water tray below the rack. This water is important for keeping humidity.
4. Sticky the thermometer inside the box so you can watch the thermometer degree.
5. Install the lamp at the top box. Use 40 watt lamp. Check the temperature and keep the temperature not more than 40 degrees Celsius or the eggs will be burned or well done.

How to operate the machine

After you finished the hatch machine, you can try hatching the chicken eggs.
1. Turn on the light. Be sure that the temperature should be 101 degrees Fahrenheit
2. Fill the water try with pure water.
3. Put the eggs on rack. Be sure there is a space between the eggs.
4. Close the machine door
5. Scroll the eggs three times a day
6. After 21 days, the eggs will be hatched. Let the chick for one days and you can remove the chicken to the brooder cops.