If this has been talked about before, please just direct me there. 

I have a new to me house with a dozen remodel can lights installed(IC).  They of course didn’t air seal anything.  I was thinking of using terra cotta flower pots with a bit of spray foam to seal them shut.  They would let some moisture through, but not a lot, and they would definitely seal each hole.  They would be ok with temperatures, being fired clay, and not terribly expensive as well.  Am I crazy? Should I stick with taped ridgid insulation, or those $20 fiberboard cups?