I always feel bad when I come home from work and my cats are just like. You were gone for forever. I counted. (Then I walk into the living room and am greeted by a pile of cat vomit, and I don't feel bad anymore.
Cat shelves or cat walls? No matter what you call them they are the coolest diy cat idea I've ever seen. Cat climbing shelves are a great way to make something cool for you cats & save space in your home.