So I know what I did wrong, i'm getting/gotten most of the pieces I need let's take our time and make it nice and clean ;-).
One of the key pieces the motherboard tray. Pretty much the most visible piece outside of the computer itself.
Took a 5mm white piece of plexy, cutted it to atx size and made every little detail needed to make it functional.
Salvaged an old tray for the back. As the main probleme from the last build was heigth i cutted it down as much as i could and spray painted it black.
Took then a 2mm piece and cut/glued it to hide the holes and gaps.
Then fitting it as best as i could to a nice piece of wood.
The wood easily comes off so i'll postpone the painting for the end.