I've been thinking of doing something like that for my two. One had her claws removed when she came here, but the other one claws madly at his now not so nice scratching post.
I think I'd use plywood and either plastic rounds from Home Depot or Orchard Supply. Or maybe some of the pressed paper rounds (that's what it looks like) that I saw in a yard sale a few months ago. And of course some odd cuts of carpeting that matched my own carpets, more or less. These would be connected with glue and screws, pre drilled for ease of getting the screws deep enough.
Yours must be interchangeable. Looks to me like several different ways to make a feline happy. How does it stay together? My cat hurls himself into his small one, and he's
heavy enough to move it across the floor that way.
Yours is certainly pretty though, I love it.