The family that lived in my house previous to mine were music lovers. As a result, they installed two 8" ceiling speakers in every room of the house, including the baths! Now, in addition to the 26 chimneys commonly called recessed lights that penetrate my ceilings, I also have 24 chimneys that produce music while they leak!
In my efforts to create simple and cost effective ways of capping the speakers, I purchased some 10" sonotube and cut it into 6" pieces. I capped each piece with HD foam, sealed the seam at the cap, slipped them over the speaker and foamed them in place. Probably have less that $1.25 in each one.
Question: Could the same approach be taken with the recessed lights provided that a 3" clearance in maintained around sides and top of the can? Cans are IC rated, but obviously not airtite. Sonotubes are available in several diameters, so finding them to fit 4" and 6" cans is easy. This is far simpler than fabricating some form of box that has to be sealed at all sides, and far less expensive than commercially available can light "hats".