I'm proposing to use rare-earth magnets to retain the covers
: in place (with an appropriate leash) I've experimented a little with the
: concept, and see no reason for not doing so, so far

I know these things are strong. (try stacking 3 1" diam of these and sticking them on the inside bottom of a cast iron frying pan) But for a good hold, they have to be in contact. Will compressing some kind of gasket present a problem? Have thought about trying this myself, but have not done it so far. Rare earth magnets are fun .

Grant