Fans will be 120mm, i miss calculated its only going to be 4 fans each motherboard, so 8 in total. Yes everything will be liquid cooled but i still need some airflow. Heres a sneak peak of how they will be hidden.
Motherboard tray will be frosted acrylic.
Basically the fans will be mounted flush with the inside of the desk intaking air. This motherboard tray will be mounted directly on top of that so the fans are hidden but the air still flows out of the curved slots. I will test this at some point to ensure a good enough airflow but i think it should be ok.
The motherboard tray will then be lit up by the fans hopefully diffusing some of the light out from the bottom of the motherboard.