I have known many cat-owners who have built cat-enclosures for their cat to go outside and stay safe. A safe place in the sun. Cats love the outdoors, the chirping birds, leaves, squirrels and bugs in the grass are a strong draw for our cats. It brings out the fierce jungle hunter in them. I have seen very small enclosures with stacks of hay sitting here and there for the cat to perch on and I have seen very large, almost play-grounds for the cats to spend hours climbing, tunneling and sun- bathing. Some even have small gardens with cat-friendly plants here and there. Most of the enclosures can be accessed from a window in the house or a cat-door. In any that I have seen, a covered area was added to the enclosure to protect the cat when the sun is too warm. Water bowls were kept full at all times. The cats were vaccinated in case any wandering cats would come by to visit and possibly carry a disease along. You can never be too careful.
I have never built an enclosure but have always wanted to. It is something I will do in the future if we build a retirement home in the country. I would love to hear from anyone who has built one and has some good ideas for a first-time builder.