We build, repair, restore, and love working on, race car tubs like this one. This was a 'design and build from scratch' sports car monocoque with aluminum honeycomb bulkheads. It turned out to have 3x the torsional stiffness of the original - for no weight penalty.
And yes, that is a lot of rivets - I stopped counting at 3000! Before it was finished...
Here it is in the jig before the first rivet went in, (it was raining...):
