Note: There is a better version of this, created by Navodile, here: https://www.thingiverse.com/thing:6505124

I took the original source object and modified it to allow for double width cards.

I included a 9 slot version, which is the largest I can print, and a single slot version you can stack together to make your own version. When stacking the single slots together, you want them to be spaced 20.32mm apart to match the spacing on a motherboard.

Creality

CR-20 Pro

No

No

20%

Print it flat on your bed and you won't need supports. I used a brim to help avoid curling at the corners.