the petromalt or femalt or whatever the cat likes should be a consistent 'treat' because it does help things move out. I had a cat get really 'stuck' with hairballs, and once I went to regularly dosing her, the issues eased quite a bit. then again I had one cat that ate a whole tube of it (remember the 'tin;' tubes for things? They slit with a cat tooth....). She was one slick cat for a while.

I do not know if it is possible to cat proof a house from a fiber eater... because aside from the crafts, there are hats, scarves, etc. that they may try to get to.