The "Show us your scratching post thread was closed, so I'll post it here and see where it eventually ends up.
Here's a post I made from a cardboard tube from a carpet roll, 150' of 3/8" sisal rope, scrap plywood shelves from the Habitat for Humanity Restore, steel corner brackets, and one heck of a lot of carpenter's glue. (Because a woman's gotta glue what a woman's gotta glue.)
Here's the link in case the picture doesn't show up:
Then I attempted to replace the cardboard inner scratcher from the roller track toy, because Saxon is incredibly destructive and goes through about 2 a month. (Seriously cat, it's for claws only, not claws and teeth together!)
I cut three circles of cardboard to the diameter of the inside, and glued two of them together. To the third one, I stitched the end of some 3/4" manilla rope at the center using an upholstery needle and several thicknesses of thread, then glued it in a spiral around the cardboard circle, ending up with more stitching through the cardboard at the end. I also tapered the cut at the end to reduce bulk.
It looks good, but unfortunately he doesn't use it so much as the cardboard inserts. I may have to go back to the drawing board and try with the rougher sisal rope.