I finally completed the case. Here are some photos and later on, a video of the whole assembly process.
Here are also some Photos of the Case with my Arduino Powered LED-Strip inside.
I also installed dust filters to the front and bottom fan as well as the GPU-side.
But I need to find a better way to keep the GPU from pushing against my dust filter, than using some small 3d-printed screw-caps i “stole” from another project.
As this is some weeks done already, i also got an SFX-PSU and printed a small adapter-frame for it. Now the case is way less cluttered and lighter.
I also changed the orientation of the Front Fan to pull air out of the case, which lowered the temps by a whooping 5 degrees (Celsius!).