Custom GPU Questions

Okay, so i have decided to use 2mm aluminum for my gpu backplate and im just wondering if it was okay to make a gap out of the aluminum to have room over my PCB and then covering it on a higher layer where it doesnt touch the PCB. Would that still not be good for my PCB?
Gpu = MSI Gtx 960 2gb OC.

Are you asking if you can make aluminum standoffs?