I found wall mounted steps on amazon and thought this could totally been done with 3D printing. Please use care when printing and mounting, use drywall anchors or mount into studs. High infill is a must for strength. 

If needed scale it to fit your cat better, my cat is small and they fit her well. 

There is a cutout in the step to fit the provided honeycomb insert or if you would like use the insert as a template to cut small pieces of carpet to glue onto it, that would work nicely and double for scratching. My cat really enjoys them :)  

*I added a second option with additional support on the bottom that should help prevent flexing for larger cats. (I would recommend this one)

*I added a 3rd option called MEGA, It is huge and will take a while to print and use a lot of filament. But it will allow users who want to print in the horizontal position to do so without supports. 

Here is the link to the scratcher mount:

https://www.printables.com/model/761172-cat-scratcher-wall-mount