Yes, this Kleinhorn is on the cover of _audioXpress_ this
month and links are available at Full Range Driver Forum
as well.

There's another "Big Stuff" project by Nelson Pass called
the J-Lo. ir was also in _audioXpress_ and features a single
EJ Jordan 92S in avery large backhorn... but at least the
J-Lo is built out of standard plywood sheets with no bends.

It's sort of like building an Arc in your basement.
The problems moving such a construction must be considerable.