Protective cover to protect a micro SD to SD extension cable plugged into the micro SD slot.
I designed and built a mount to fit the SD card reader onto the control panel of the Ender 3, see: https://www.thingiverse.com/thing:3451823

The plug in the micro SD slot is very exposed, and easy to damage or bump out of the micro SD slot. While there are several designs on Thingiverse for protective covers, most are very bulky and block the USB slot. I therefore designed an extremely slim protective cover for the micro SD plug and also to secure the cable. It does not obstruct the USB port, nor does it obscure any vents of the electronics enclosure.

To achieve the very slim fit, I modified the micro SD plug to minimise how far it protrudes from the micro SD slot, and also to enable the cable to run under the electronics enclosure. This results in the micro SD plug only protruding by approx 5mm from the slot when connected.
The method I used to modify the micro SD plug was:

1. Using a Dremel with an abrasive wheel, I cut off approx 3mm from the wide end of the micro SD plug, close to where the cable is soldered on, just to remove the un-necessary length.
2. At the point where the plug tapers from the width of the micro SD card, I scraped the paint/lacquer from the copper tracks on the top and bottom of the plug. Ii scraped an area approx 3mm wide. This is to provide clean exposed copper to enable soldering.
3. Using a dremel with an abrasive wheel, I cut almost all the way through the micro SD board: all the way through the upper tracks and the fibreglass board, but not through the copper tracks on the under side.
4. i then bent the board down at 90 degrees, and ten applied a small bead of solder at the bend point on the under side tracks to strengthen the bend. Take care not to short between tracks.
5. I then soldered some fine wires over the bend on the upper side to reconnect the tracks on the top.
6. Once all tracks were reinstated, I applied black cyanoacrylate glue to cover the exposed tracks on both sides at the bend point.
7. I was then able to mount the SD reader in the control panel mount (https://www.thingiverse.com/thing:3451823), and route the cable under the main electronics enclosure to the micro SD slot.

To fit the protective cover, remove the screws from the front Y axis belt pulls, and rotate the pulley bracket out of the way. Slide the cover in from the front. It is a firm fit, so that it "locks in place" when fitted.