That's a cool shelter. Compare to my mom's, which was an imposing fortress: A huge cardboard shipping box weather-protected with plastic film and tarps. She cut a square out of one side to create an entry. A deck table served as a weather roof for the entry and for feedings when conditions allowed. After the cats got used to the set-up, which was quickly, she added a piece of thick towel secured inside the shelter's entrance from the top, which they could push aside when coming and going. Inside there were many piles of straw and a few old blankets. No food, water, or litter box. The box was on her deck under an eave and further insulatted and wind-protected by hay bales along the sides and top. The cats shared this shelter all winter long. And they survived -20 and -30 F nights. When spring arrived, mom just packed up the whole unit and put it out for the trash truck, and made another one the following winter. She figured correctly that a.) cats are smart, b.) they like boxes, c.) and they like small entryways, which they apparently perceive as cat-like and safe. She considered adding an escape hatch on the other side, but never did.