For two cats, i would do this spuble long and keep it umder a window sill, drill some holes in the back so it can air out, keep both sides totally separate so the cats can have their own space but also keep everything together for cleaning purposes.
My husband built one of these for our feral cat "Ghost Cat". He, and the other strays, have used it every winter and on rainy days. It is easy to make and they seem to like it. Outdoor cat house shelter for outdoor cats
Wrap some baker's twine or other string around a wooden block to create a graphic textured stamp. -can also use rubber bands- Stamp on inside of paper bags from grocery store or paper that comes in mailed packages, use as wrapping paper.