All metal hardware should be lead and zinc free, including bells. Beware of the clappers inside of bells. These can be removed easily by most birds and accidently swallowed. Round rings should be too large or too small for your birds beak, head, and toes to catch. Split key rings should be removed from all toys.
Parrots can easily separate the metal and entrap toes and beaks.
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. Make sure the wood used is listed as safe for birds. Some safe woods are Apple, Arbutus, Ash, Aspen, Beech, Birch, Cactus, Cottonwood, Crabapple, Dogwood, Elm, Fir, Hawthorn, Larch, Manzanita, Pine, Poplar, and Willow.