Do yourself a favor and plug up that hole right.
What you want is electrician's putty, or duct seal.
This stuff, exactly.
It doesn't get hard, doesn't shrink, you can remove it later if you want to convert your humidor back to a fridge, and a pound block of that stuff will last you a lifetime. It never goes bad.
It's like duct tape, good for a million things. Like sealing holes in the house where pipes and wires come in, or if you make holes in the car for speaker wires, you name it.
There should be a lump of that stuff in every junk drawer.
