Cheese cloth might hold water but it would block airflow, I wouldn't suggest it. If you saw how big a normal hatchling ball python is compared to the holes in the light diffuser, you wouldn't put a second thought toward it. A runt ball python might be able to slip past, which is where I do like the idea some plastic mesh under the light diffuser that should be able to stop it. I say under, because the egg would still get the same airflow.