Outdoor Shelters for Feral Cats

I lost my information on how to make outdoor shelters for feral cats. Can anyone let me know the different ways. Thanks

When I built a shelter years ago I took 2 boxes one bigger than the other; I lined the outside of the small one with styrofoam or any insulation;then slip the bigger one on the small one and cut out a door. Make sure the door faces away from the wind. I made it face the wall. I put a comforter inside, but recently I found out that hay is a better way to go in terms of keeping the heat in...and won't get wet. Good luck

If you google 'feral cat shelter' or just 'feral cat', there's lots of stuff on the net.