I drew something up in SolidWorks to get an idea of the outer shell. Right now I am thinking of a layer cylindrical shingle design. This would allow the enclosure to shed water, but would allow air interchangeability for the air quality sensors.

I added as top status indicator light and an internal light pipe that would probably look really cool if it was running a color flow sweep. If these parts were injection molded it may have to multiple snap together pieces, but I am noddling around with some other ways to make moldable lover vents that can utilize one die set.