How can I make an outdoor cat box?

Got to either Lowes or Home depot and get lrg black cement mixing tub,or for one with lid use really big sterilite or rubber maid container cut hole in upper side(if out in elements) or top if in protected area porch or such. Fill with dirt from yard or litter

To get started on building an outdoor litter box, you simply need a frame of four walls that are the right height for the type of cats in the area. If there are kittens, the walls should be lower so they can climb in and out easily. Don’t worry about building a bottom for the litter box because you will need to allow for drainage. As for the litter itself, don’t use conventional litter, which absorbs water and will be ruined by the weather. Instead, use sandbox sand that you can find at most hardware stores. You’ll only need enough sand in the litter box for the cats to comfortably dig, which is a major attraction for cats.

Perhaps this will help https://alleycatadvocates.org/communitycat-care-center/creating-winter-shelters/

I bought a larger "coleman" cooler from Goodwill. Cut a hole in one end and lined the cut edges with Pipe insulation. Turned it upside down so the widest part (top) becomes the bottom. Put a towel, blanket and on top I put a pet heating pad (Amazon). Taped up a thick wash rag over the door and my cat stays warm and toasty. He LOVES it!