This document provides instructions for making inexpensive and warm outdoor shelters for cats using large Styrofoam coolers. It describes obtaining the coolers from various sources, cutting an entrance hole and reinforcing it, wrapping the shelter completely in thick black plastic sheeting and sealing it with duct tape, orienting the shelter to block wind and moisture from the entrance, and filling the interior with dry straw rather than fabric that could freeze. Lastly, it offers tips like using catnip to attract cats and weighing down shelters in windy areas.