I designed this Micro SD card storage wallet as I wanted a slim credit card sized storage that I could put in my camera bag. It holds 12 Micro SD cards and a single standard SD card or adapter.
It is designed so that both halves are printed together there is a sufficient gap for the hinge to work.
I have now created a half size version of this as I felt 12 micro SD may be too much for some. See https://www.thingiverse.com/thing:3860252
Once printed it may need a Little freeing up of the hinge