I need to make a 6" circular hole in a wall that goes between a room and a walk-in closet for a portable air conditioning pipe. It is in a basement and the pipe needs to be exposed spiral (like in a commercial application) because I don't have room for soffits (ceiling low + other space issues). The framin is regular 2x4 studs. So I would have a 6" hole on the room side sheet and one on the closet side. I would prefer if it were not just a hole in drywall, however exactly cut, but if there was some sort of insert inside it that trims it nicely.

Any idea if there is a ready product like this or that can be ordered and, if not, how would I go about fabricating one? Imagine a round window without the window glass part, just a hole trim.