Castor oil repels rodents.  When diluted and sprayed over the ground,
it also works on lawns and gardens to repel voles and moles.  One
could probably permeate cardboard or some other substance with it
to place in the bottom of a console.

It does have an odor of its own, albeit not strong.  It's neither
pleasant nor particularly offensive, at least to me, but one could
remove the permeated material if it is found to be offensive.  The good
thing about it is that it drives the rodents away and doesn't kill
them, so they aren't crawling off to die and decompose somewhere
nearby.

Castor oil is cheap enough over the counter at the drugstore, so it is
worth a try.

Patty Slayton
Moore, ID  USA