There is alot of threads on several type of home made cookers. Check the search function, if it was not so late I would post the links to a few of them. Also know that a hubovator is very inexpensive and is worth the $$. You may want to go that route as well. Hope that helps.
Suggestion: Try to find a temp. for females in a room area some place. (no incubator). Mine is near a gas water heater that is pretty constant and stays 80 to 84 degrees. I have hatched all my females that way this year. Eleven for eleven so far, with eight eggs in there now still to hatch. take care. HJ