We didn’t follow the instructions exactly. My brother is a builder and had his own ideas!! I was a bit nervous, but it turned out well. Our boy is still learning how to use the cat flap but likes going out there.
We usually suggest and supply only tension cords for each external corner, but “the builder” has also incorporated white PVC pipe as you can see (not a bad idea at all). The under eaves cat enclosure are the least expensive of all.