2X SD card holder with hole for keyring

Update: Printed in PLA, and couldn't get the hinge to open/close. So I'll have to tweak this (later).

I liked mikeprusa's SD card holder design because it closes to keep the cards clean.

I added a tab with a hole in it so that I can attach a keyring, to be able to clip it into my camera bag - don't want to lose the cards when I travel.