A few more things, if you're able to find them in your area at toy stores or yard sales.
I find that some children's toys, the Little Tykes brand have very hard plastic and durable toys. Just be cautious of the ones you get. Like with any toy you give your dog, the must always be supervised when playing with it. I have a Little Tykes toy piano my dog likes to play sometimes. Here's a pic of an example of one. She only gets it to play with when supervised.
Toys"R"Us - Baby Tap-a-Tune Piano