Not him but very like it, separate boxes without the use of rulers- and my recall that he was a he or even European may be way off. Saying European just usually means not British if you are British-lol.
I’d like to see the tools/material list, always helps. And I think there is more work to be done on the front panel, not that it needs it as of now but I bet you return to the case once the ‘thank god I’ve finished’ feeling wears off a bit. I think once the OOD is out the way then the options open and it isn’t that hard to make a whole new front panel when it is just USB ports, the switch (although I prefer the back for that) and maybe a LED.
It’s your build but I, in the past, have used just aluminium sheet (guillotine cut which at least gives you straight if not laser quality corners) and stand-offs. So, around the edges are say 3mm of gap for air and the flat front looks nice. I also fancy trying copper but the cost has put me off so far- stainless would be great but I don’t have the tools to really deal with it. I have a little template for marking out the holes for the USB sockets and that helps. For the Raspberry Pi I have a set of templates for all the holes which s almost cheating really, and as most SBC follow the Pi, they get a bit of use.
Ultimately though this is a nice build that takes an OEM, makes it a bit different and its affordable and usable. I have a u5 based Lenovo not doing anything and it has inspired me to take another look at that. However, it is sub-ITX, more mini-PC so I won’t be squeezing any dGPU in the case, maybe a case design might change those options as I do have a spare 1030 that would suit it (depending on any PCIe availability).