I have shelters for my cats in the colonies. I use plastic storage bins, the kind you use to store clothing. Then buy the cheap styrofoam coolers as they provide insulation. I cut an opening in the plastic storage boxes about center. I cut the sides along the cooler and place them inside the bins and put both lids on (the cooler and bin). I put straw inside them and lots of cat nip to help encourage them to go inside. In all three of my colonies they have been a hit and are used. I actually bought Christmas ones at K-Mart when they were marked down this year to replace some of the older ones. . $10 ones for $4...what a deal. I change out the straw a few times a year. I also use them to protect their dry food from rain. I turn a couple on their sides and put the food bins inside.