Well then, if he can do complete floors, how would front fenders then be? Roughly same size, same investment, but likely smaller market?
Seeing them advertised for 3500 euro now in germany ( I know, asking price likely is not sales price)
Secondly, how about the thick metal reinforcement in the strut tower?
Not available elsewhere, but no too difficult to fix as welding thick steel is easy.
Thirdly, and most interesting perhaps:
I myself struggled to create the horizontal floor section under the corners of the rear seat, where the thick verticale metal pins go through the floor holding the rear axle. It's a complex 3d section, about 1 by 1 foot would do, and no-one makes it. All known floor replacement parts end just shy of this problem area.
As it is an open area under the car, close to the wheels, with originally a foam that disintegrates. One of the first places where rusts starts on e9's.