The following witness report of the collapse of 7 WTC, that included a mention of buckling, is taken from the blog https://undicisettembre.blogspot.de, recommended by @Oystein in another thread:
Undicisettembre: Did you see WTC7 collapse? What do you think of it? Did you notice anything...
Here's a duct for a JT9D someone made into a mirror. They don't say which JT9D, but they do say it's from a 747.
http://www.sportys.com/wrightbros/all-categories/boeing-custom-hangar/747-jt9d-engine-tobi-duct-mirror-gray.html
Few sights are more inspiring than that of a mighty Boeing 747...