The Kitty Pass Interior Cat Door from Amazon capitalizes on this with ... DynamiteDesignLab's Custom-Designed Thru-Wall, Interior Tunnel from Etsy. Although intended for cats, some small dog ...

[Dino] continues his to satisfy his weekly hacking goal by building a cat door for his pets. He has a Habitat For Humanity resale store nearby that was doing a 50% off sale on doors. So he picked ...