Update: Please try version two of the main piece, as it now has a larger 2040 attachment for a tighter/stable fit to prevent it from sliding. I was going to make the lid looser but discovered it is great for keeping the forces from pushing the slot at the front forcing out the lid. However, if you wish, I can make a version two with a slightly looser configuration. I recommend NOT pushing the lid all the way, leave some space to remove it easier with something like a screw driver. :)

This uses the cheap micro SD card cable extensions you can easily buy off places like ebay. The use of the cap is optional, as it is a rather tight fit, but be careful with the cap as the tolerance is quite small at 0.3mm (offset boundary) and not that easy to remove. But once in place it stays and keeps the piece stable.

It is designed to be fixed to 2040 profile slots and I put it underneath via the Y gantry. I have my printer higher with squash feet but the dimensions of this design are so small that it should work without the feet even I believe.

I would like to clean up the cable that hangs out in future, possibly with a printed plastic clip. Also, possibly a micro SD card slot holder as seen on similar designs.

Your mileage may vary. Feedback of all kinds is appreciated.