I stole some clips off of one of the security dongles and it fits perfectly.
I mount mine on the inside of the cage and it will slide in perfectly behind the heatsink so the ribbon cable is perfectly lined up.
Hope this is helpful for others.
Awesome work as always @Darksoft , I love this system thanks to you.
STL attached in the ZIP.
Please do NOT sell these, personal use only.
Source: https://www.arcade-projects.com/threads ... der.28008/