Looking for small adjustable vents for cage.
 

Hi all,
I'm working on some custom caging for my snakes, and I am searching for an adjustable vent that would allow me to dial in my airflow/humidity. I'm thinking something along the lines of a car vent or a small HVAC register that has flaps that can be opened and closed.

Anyone know of anything like this?
Thanks!

Your best bet might be to drill holes and build a couple rails that you can slide a cover open and closed over the holes. I did a somewhat quick search and the only small adjustable vents I could find were sold on alibaba which wouldn't be my first choice in purchasing.