Spool Louver (WIP)

Summary WIP WIP WIP OK, so I have a grow tent. I bought it as an enclosure for my HE3D K280, a massive beast of a printer. Once COVID kicked off, though, i figured I wanted to make it into a sanitizer for large items, groceries, amazon boxes, clothing, etc. I put a room ozone generator, a UVC lamp, and built a purge unit out of an old ventilator fan off some ancient piece of equipment (steel frame? check. High CFM? check. Loud as hell? double check) and a dryer vent cover. i automated it with some smart plugs and an Alexa routine, so I can put everything in, seal it up, walk away and let the robot run the machine. Problem is, purging will pull a vacuum on the poor tent. All the flaps and ventholes are sealed to keep O3 IN, and they also keep O2 out. So I needed a self actuating vent cover that wouldnt take forever to print. I realized that discarded spools (why do I have so many?) fit the holes perfectly, and only required a 70-something mm hole. So thats what this is. A self actuating