We've got a couple very coarse mesh bags that are maybe 12" X 6", that are made for laudering delicates in the washing machine.
I'm eyeing them as hops bags, especially for dry-hopping with whole hops. The coarse mesh should allow plenty of contact with the wort while holding most of the leaves in. I'm thinking I could put the bag+some marbles in the carboy (rolled back over the opening), stuff the hops in, and then draw it closed.
I may try it for boiling as well. Since we have two, I think I can pilfer one more-or-less unnoticed.
(Of course, I'd gladly keep my mitts off these if it meant they were actually getting use to wash the kind of stuff I wish she had to wash more often, but that's another matter.)