Get something TALL with a perch on the top. You can make something as well, if you are inclined that way. Sisal rope or carpet work well. I prefer a perch with sides so they can't fall off. My RB Amber used to fall asleep, have his head over the edge, and next thing, BANG he fell off. He did this over and over until I finally modified it and put sides on it. Still have it, 14 years later! The rest were purchased or made after that so they came with sides.

Tall because a kitten grows into a CAT who wants to stretch up as if it were a tree in the forest and rake those nails downward.