Simple and cheap cat climbing tower

This cat owner made an epic indoor play tower using a 4x4x8, a piece of (open loop) carpet large enough to cover it, a piece of plywood cut to size and some 2"x2" strips to secure it to the wall. She then stapled the carpet to the boards, secured the plywood to the 4x4, attached the 2x2 strips so they'd hit a wall stud and then screwed the 2x2's to the wall. Check out the amazing result!