Hi, im new to the forums, this couple month i start playing with sketchup and came out with this same layout but you nailed it. You did an awesome work, love those 3D printed attachment idea.
Playing with this layout for quite long time, i think it would improve a lot the airflow of this layout by adding exhaust hole on top of the case.
Now looking at your case seems like there's 2 intake hole for the CPU n GPU and no way for the hot air out, the hole above the motherboard IO will kinda help for the CPU side hot air but the GPU side there's nothing, only the PSU sucking the hot air out and this can let the PSU hotter which will increase RPM of the fan of the PSU and the noise.
I think adding hole on the top panels or maybe couple slim fan can help too. And you can add intake hole in front of the PSU (bottom panels) for better cooling for it and maybe can lower the noise level.
Sorry for my bad English if there is error, i don't talk or write English.
Thanks for the response! Your english is great. In regards to the cooling, I was getting below 60 degrees Celcius in Aida after slightly undervolting my AMD 7890k. To be fair, I only ran it for 20 minutes to get to a steady state, so the acrylic could trap heat and the temperature could slowly increase over time. Although there isn't much cooling in the CPU chamber, the case never felt warm after several hours of use - I don't really know the thermal properties of the acrylic but it might be aiding in heat transfer. The thing I worry about most is the VRM's in the system. I'm running a top down cooler so I might get a little airflow but not much.
For the GPU side, I think it should be fine. The Flex ATX exhausts out the back so it is a pretty enclosed system that doesn't need much airflow. As for the GPU, it is right next to the grill, so temps should be fine thanks to a direct airflow path (it's essentially like the Dan Case grill, which seems to have fine temps.)
One way I think could really improve temps would be to add a large slim
140mm fan on the CPU Side and then use an
LP53 heatsink, I'll have to check fitment issues, but worst case scenario you just have to widen the case a few mm. That's a pretty easy mod, and could be done by editing the step files, or the DXF's.