Destroying litter boxes

[Niomi]

My mini lop cross Downy has a new habit of chewing up his plastic litter boxes. He has hay, wood toys and tree branches to chew on, but he attacks his litter box. Yesterday he stopped eating. There were shreds of plastic all over the floor from him destroying his litter box. I was worried he might have swallowed some, and I took him to the emergency vet. The vet gave him fluids and medication, and he is better this morning. I need to get rid of the plastic litter boxes. What else can I use?

 

[Preitler]

Is the rim of the box an obstackle, higher than the level inside and outside? If yes I would put wood blocks or ramps around it, at least as high as the litter box is, so that rim isn't an obvious target. I use a under bed storage box, with its filling of wood stove pellets and wasted hay it's almost full.