I had a solid cupboard door, a large bucket full of water with a brick in it , but I am afraid my monsters broke through the lot. A bag of litter would have just been shredded and strewn across the floor I am afraid (I have seen what they can do with the 7.5 kg bags of dog food and it's not pretty ... (and yes I recognise that food is an incentive, but so it going outside ....