An empty cage or aviary cannot be used; you need to fill it with perches, toys, food and water bowls and you need to put some hygienic absorbing bedding on the floor.
Perches
A cockatoo needs perches to sit on. These perches are preferably made of wood, as this is warmer to the touch than metal and can also be used to chew on. The perches should be as big in diameter that your cockatoos feet circumvent only half to three quarters of the perch. A perch that allows the front and back toes to meet is much too thin for a permanent perch. You should provide your bird with multiple perches of different diameter to strengthen the feet and wear down the nails effectively. The perch should be big enough so the cockatoo will not reach all the way around it, but rather 3/4 ths or halfway around it.
Always keep in mind that perches are for temporary use; it is normal that your bird will chew on them and eventually destroy them. This is part of a fun life for a cockatoo. You can choose to buy one good perch made of very strong wood, and provide other perches of lighter wood e.g. of willow, beech or fruit trees (never provide branches of pine trees / conifers). You don’t need to spend any money on them, as you can collect them from local trees.
Food and water containers
Of course the cage of your bird needs to be supplied with a bowl for water and one for food. Best is even two bowls for food; one for dry foods and one for wet food like fruits. You can choose between bowls that can be placed on the floor or bowls that can be attached to the bars of the cage. It is better to hang the bowls from the bars of the cage, as a cockatoo likes to eat in a ‘safer’ higher place instead of the floor. Generally a bowl placed higher will also have less chance of becoming soiled by feces.
Cockatoos sure like to break things, so make sure to buy durable bowls that are very hard to detach from the side of the cage.
Toys for cockatoo cages
A cockatoo need toys inside his cage to keep him busy when he is bored. Even if you take him out of his cage a lot, he will still be spending a lot of his time in there. Even when he has another cockatoo as a companion, he should be able to play with something inside of the cage.
Luckily a toy for a cockatoo can be basically everything. Favorite for any species of cockatoo: something that can be destroyed. Cardboard boxes to shred to pieces, bells-and-chains that can be disassembled in half an hour, a dog floss made of cotton that can be pulled apart, wood to chew to bits, a box made of reeds and much much more. You can also buy specific parrot toys, but do not expect them to last long. The number one criterion for toys is that they are safe for your cockatoo. Check out my page about Toys to get an idea of appropriate toys and how to make your own safe toys.
At the bottom of the cage
You have to cover the floor of your cockatoos cage with bedding to absorb the droppings and leftover food and what allows for easy cleaning of the cage.
Generally bird sand, wood chips and flax bedding are preferred by bird owners. Sawdust is too dusty and light to be handy as bedding. One big flap of the wings and your cockatoo has changed his cage bedding into your house bedding.
A big aviary usually has a bedding of sand, small pebbles, outdoor tiles or natural growth e.g. grass. Make sure the floor of an aviary does not get too muddy, if it does you should consider heightening it with extra sand or tiles. Mud or standing water can be a source of infection for cockatoos.