TeachingTech made a really nice replacement case for the Ender 3 printer (thank you!!). It allows for the use of a Raspberry Pi and a couple of different replacement electronics. I just wanted to use the MKS Gen L board so I created these plugs to plug up the unused Raspberry Pi cutout and the non-MKS board SD card slot so that the fan would properly draw air across the stepper drivers as intended. I actually used the case pieces to properly shape these parts so the fit should be right on.
Jun 19 '19- Original file will work but not "perfect" so I tweaked it a bit to make the plugs easier to print (eliminated the overhangs), the SD card plug easier to install, and the Pi hole plug stay in place more securely.
whatever you like Same as your case
Same as your case
This was a quick and "dirty" design in TInkercad . It was easy to bring in the original files and use them to shape the plugs, then clean up the elements to make it easily printable.