Place the large Styrofoam cooler in a box that is about the same size and tape closed or line the box with sheets of Styrofoam cut to fit.
Cut a round doorway about six inches in diameter in one of the long sides of the box, cutting through the box and Styrofoam (Do not cut the hole in the center as the wind will blow straight in). Make sure to cut the circle towards the side and high enough so that the bottom of the doorway is several inches above the ground.
Cut a piece of the plastic sheeting to completely cover the box. Wrap the box as tight as possible and secure all loose ends with Gorilla tape. Make sure to cover all openings with tape to make the house as water tight as possible.
Cut the plastic sheeting that is covering the opening like you would cut a pie. Use small pieces of Gorilla tape to secure the plastic and make a nice smooth opening.
Stuff the bottom of the box with straw.
When placing the shelter face the opening away from the prevailing wind direction. The shelter is fairly lightweight and may need to be weighed down. Catnip can be sprinkled inside at first to attract the cats.