My cat's favorite thing to claw on is the variegated cardboard blocks that you find in the cat department of pet stores. I tried the ones that are supposed to be like files for their claws, but he didn't like it at all, so that purchase was for nothing. But he loves the plain cardboard rectangles (it looks like cardboard stacked together on end and glued and cut into rectangles). I tried a scratching post, two, in fact, but he didn't use them at all.