You'll find that alot of pre-made toys have rawhide on them, I buy those little rawhide shoes and pigs ears for my birds and they love them. Anything you buy from a petshop you should make sure the of the following - Leather pieces and strips should NOT be dyed and should be vegetable tanned. Other tanning processes use chemicals that are toxic to birds. Rawhide should be un-bleached. Avoid the flavoured ones though as they tend to get a bit whiffy
I use the little rawhide shoes, and stuff treats in them. None of my birds are that interested though.
I bought a giant bunny willow ball, and hung it in Biggle's cage. Stuffed it with some banana chips and raisins. It already was stuffed with hay. Once he had chewed through most of the ball, the willow twigs were still rounded, and on the floor. I then made a round swing, by wrapping the willow twigs round with raffia. He loved that, but of course chewed through it. The hay ended up in, Ziggys forage box