What if you transmute the apparatus? I mean, changing iron into bronze isn't even that high a spell level is it? Or plastic. Or bronze wood, if you feel like dipping in on Eberron. And why bother with a Rust Monster in the bag of holding? Fill a pill with those feather charms that turn into anchors. Or do both and fill the thing with rust anchors. Even if they have waterbreathing let's see then avoid tetanus then.