I spent $200 having a chicken-wire shelf put up on the wooden fence around a large yard. My 12 yr-old "baby cougar" jumped the gate, right away. It did keep neighborhood cats out.
They don't make cats like they used to. There's more wildcat & exotic cat in them & in outside cats. An enclosure would have to not be easily busted. Every night, I say "don't break the window!" as my cats wrestle near the window. I can hear the "Boom" and have already been planning for when it breaks.
If the cat will be in the enclosure at night, you will have to make sure predators can't break in, as DoomsDave alluded.
It would be nice if designers would create more attractive catios. Cats are the most common pet, next to fish, in the US. ( Yes, dog people, they are. :smile
