There's a bit more of that on the German forums e.g. https://www.computerbase.de/forum/showthread.php?t=1279570, http://extreme.pcgameshardware.de/casemods/304695-dan-a4-sfx-das-kleinste-gaming-gehaeuse-der-welt-update-12-12-2016-a.html and...
I assume PCIE bifurcation would work for 1 graphics card plus a 10gbe adapter? Could an M.2 socket with the right cables and adapters be used for the network card instead?
Taking a quick look at prices in the UK for a 1000 x 1000 x 1.5mm sheet you can see why stainless is not so widely used.
Mild steel: £15
Aluminium: £24
Brushed stainless steel: £64
Not saying it wouldn't be a nice option.
As well as being shielded I'm pretty sure the riser cable can go either side of the motherboard/graphics card panel.
Edit. The computer base review pictures show this in fact
If you have access to CNC laser/waterjet/punching/bending tools and Lian-Li-levels of experience in using them then why not.
Using a short graphics card might leave room for a 3.5" drive mounted vertically behind the PSU.
I attempted to overlay an image of the Cryorig C7 onto that Asus motherboard.
The SupremeFX module might interfere with a low-profile cooler unless it's removable.