Cat Tree. DIY. Homemade for Cats.. This is what I am attempting this weekend @kevinlittlejohn
Cat Furniture, Cat Trees, Cat Condos, Cat Towers, Cat Tree Condos - NW Cat Trees
Cat tree - for real. This would look great in the house, much more decorative than the carpet towers sold at the pet centers, and the kitties seem to be enjoying it! Craft store tree, handyman platforms, totally do-able.
Cat Climbing Tree (Mille Makes), with link to construction pictures