Box Kitty is a set of modular rugged cardboard pieces (they're scratch and waterproof) that attach via Velcro so you can build your cat the cardboard castle of his or her dreams. They're currently crowdfunding via Indiegogo and the most basic set starts at $55. I'm going to build my cat Merlin the most amazing wizard's castle, he deserves it. "You don't have a cat named Merlin." I just renamed my existing cat Merlin. "You can't do that." Why not? I never call him by his real name anyways. I guarantee he thinks his name is Here Kitty Kitty. Now I need to get him one of those conical wizard hats and both our lives will be as complete as they're ever gonna get. "That's sad." You don't have to tell me.
Keep going for a couple more shots and some video of the possibilities.
Thanks to Leslie P, who just gives her cats the boxes Amazon orders come in and lets them build their own forts.