This is a personal choice; if you require something sturdy, then opting for a box that is made of metal like steel can serve your purpose. And, if you want to get something that is foldable, you will need to get something in a fabric form like a canvas or cotton material. The idea is to buy a storage box based on your utility. Just remember to ensure that your product is made of a chemical-free material so that it is safe for your pet.