I made a cat tower for my cat Lily with a crow’s nest style bed on top. The initial design, shown below, had a nice “railing” with a lip that allowed Lily to rest against or peek over the edge without risk of falling out.
Unfortunately, it proved to be too fragile. Then during a move it broke beyond repair. For awhile I left it railing free with the bed “secured” to the top with Velcro. One day kitty rolled over in her sleep and fell out! She was fine, but it was a long time before she used the bed again.
My new design is a lot simpler and less fragile.
No glue or fasteners are required. The rope keeps the “ribs” from being able to come off. I generally like how it looks. I am not especially happy with the knots in the middle of the “doorway”, but it’s good enough. More importantly, Lily can’t accidentally fall off her tower in her sleep.