Bird Toys for the Destructive Ones

I have an Umbrella cockatoo that destroyed every toy I purchased for him. I would spend $35 for a "bomb proof" toy and it would last about an hour. For a while all he had were pieces of manzanita (which hold up faily well), pine 2 X 4's to make toothpicks and a large sterilized beef bone. Then I tried a cluster of baby teething rings, hard plastic. That was 4 months ago and they are still intact.
So if any of you large bird owners are stumped for toys, try the baby department. Much cheaper, also, than bird toys. He loves them because he can shake the rings and make noise and can hang them over the end of his perch on top of the cage. They also make great bombs to drop on the cats. There is one kind that are rings that can be snapped together to make chains. Each ring is about 3 inches across. Check it out.