Commonly people will insert a length of hose into their grow tent air vents and create an S to block light, but this insert will do the same thing acting as a light baffle. This fits very snugly into my AC Infinity Cloudlabs 866 60x60x80 tent (5x5) which I got two years ago. I don't know if new models are identical or what other models this may fit, but the goal of the snug fit was to make sure they don't leak light and don't sag once inserted. 

You can scale it a bit if you think the fit will be too tight. No tricks to printing it for me on the P1S.