>>...on the Hobavators i used to use there were two red plugs you could opt to leave open for ventilation. another person told me having air holes was a bad idea. any suggestions?
Not exactly a BAD idea, but normally unnecessary for reptile eggs. If you're thinking of needing air exchange, you'll probably be opening the incubator door and opening the individual boxes to check on the eggs a sufficient number of times during incubation to provide all the oxygen those eggs could conceivably need. So in that scenario, holes in the incubator would serve no purpose. In fact, if you had holes in the egg boxes and holes in the incubator, you'd have a little more bother maintaining high humidity (for snake eggs, anyway).
On the other hand, have you considered that you might use the incubator as a temporary cage in the future? Over the years I've used mine in an otherwise too-cold room as a quarantine cage for newly-purchased pythons for several months at a stretch. I've also used it as a sort of hospital for certain snakes with respiratory problems, forcing them to stay at a body temperature higher than what they had been choosing in their own cages. In these cases, it's handy to have a small number of ventilation holes that you can plug up, or even just cover over with pieces of tape.
So, ask yourself what you'd need the holes for in your situation, and you'll have your answer.
-Joan