The cats are getting old and reluctant to go out in the rain. [Me too :-( ] They still need to scratch stuff to exercise their claws and clear old sheaths off the claws.
I was looking at cat scratching posts online, but they seem to be mainly a lump of timber on a flat base covered by open mesh coarse cloth. [But see
Anyone made a cat scratching device?
I do have a lot of bits of timber left over from the build, plus a lot of jute (I think) cloth used to cover concrete or brickwork to protect it from extreme heat or cold whilst it is curing.
When they are outside the cats like to stretch to their full height before laying into something wooden so many of the posts may be a little short.
An alternative is
Cheers
Dave R