Here's some pics of a portable, knock-down cat condo. This fellow breeds a certain type of high dollar cat, and needed something to keep the male separate from the females at different times of the year. The inside is covered with linoleum with the corners caulked. The outside was T-111 which ended up getting painted. The upper portion with the open studding ended up getting a green nylon mesh around it. I made a scaled down storm door with a spring loaded closure. The four walls screw together and also screw to the floor. It had wheels on it to make it mobile.