This is based on another design I found on here but is a complete redo from ground up as I wanted so many changes it was just easier to start over.

The SD card adaptor is stored in the bottom.

The micro-SD cards are easier to remove, push under the card and one end will rise.

A positive lock ‘nub’ is on the end to allow the container to stay closed. A small amount of force is required to open.

The build file contains two version of this. One with 8 slots the other with 24 slots. A simple M3 x 10mm screw is used for the 8 slot a M3 x 16mm screw is used for the 24 slot version. You could potentially increase the size further with just a longer screw.