Beehive ventilator strip version 2

Beekeepers sometimes need to ventilate their hives. The trick is to create a small opening that's too big for the bees to plug up with propolis, but too small for them to use as an entrance/exit.

The classic method is to glue popsicle sticks inside the outer cover of the hive (this is the "lid" of the hive - called an outer because there is a second inner cover to provide a way to exit the top of the hive). The problem with this is that the solution isn't reversible, requiring the keeper to