building a incubator

[Guest]

Iam bulding an incubator out of a old camper frig how many air holes do I need to drill in it

[John]

That brings back memories of my first two incubators that I made myself.  One was made from used redwood from an old kerosene incubator I bought at an auction.  I  used a heating element from a clothes dryer, plastic Rainbow bread trays to place the egg trays on and an old blow dyer to circular the air as I recall.  
FYI, the newer model GQF incubators have two holes that are about 3/4\" diameter.  Both are in the back center with one near the top and one near the bottom.  Those incubators are about 8 3/4 cubit feet, so you can figure from there for starters.  The locations of the holes in your incubator will depend on your fan location and the direction of air circulation.