Improved FLSUN V400 Fan shroud

This is a fan cover for the FLSUN v400 that is a bit further from the fan (+4mm) and should reduce a bit of the noise. 

Modified the file to add more structural support to the side-pins and also added a few more slots to enhance airflow. 

Print: Print at 0.2 layer and 30% gyroid infill.

Multicolor: Print it facing downwards and add a M600 (filament change) on layer 4 or 5 to do a multicolor print. 

Edit: I have added a sliced gcode for the v400 that does the filament change pause and prints it perfectly. (remember to load your default bed mesh in your start print macro)

Increased the number of holes, fixed geometry and also redesigned the pins portion of the design.