Thanks for sharing this, avb3.
A quibble about terminology. The part shown in Alex's photos is a stiffener, not a stringer. To those of us who design these structures, there's a big difference- stringers are deep, continuous, large-moment-of-inertia longitudinal members; the "top hat" stiffener shown there is a small
member that controls deflection in one panel without sharing in the global longitudinal loads.