This part functions to 2 purposes.
The extra SD card holder allows you to slice/queue the next print job via another SD card
I recommend using Prusament PETG Orange; it's the same filament that the Prusa printers are made from. It keeps a slick OEM look. LINK
Original Solidworks file from HERE
After installing the part, make sure to recalibrate your machine since the position of the Z-axis rail probably shifted.
The author hasn't provided the model origin yet.