Choose a metal or hard plastic-coated wire cage and make sure the wire openings are not bigger than 1 inch by 1 inch. Avoid using glass aquariums, as they prevent airflow. Make sure the cage is large enough for your ferret to exercise and play. Aim for a cage that's about 18 inches by 30 inches by 36 inches, with at least two full levels, for a single ferret or a pair. Use square litter pans rather than corner pans.
Most ferrets prefer to have all four feet in the litter pan when they use it.
At least one litter pan should be available in the cage, usually on the bottom level. Choose a wood or recycled newspaper pellet or corncob litter. Line the wire bottom and levels with newspaper or linoleum to protect your ferret's sensitive paw pads. This also makes cage cleaning much easier. Provide a plentiful amount of bedding, as ferrets love to burrow.