Prusa i3 MK2/MK3 External Ventilator Cover

Extruder ventilator on Prusa i3 slightly whirls the air on suction side of the extruder, which resolves in unintended cooling of one side of printed objects. When printing (especially with ABS), this can lead to worse bed adhesion of the object on this side.

This fan cover blocks the air going down toward heatbed. The MK3 version also masks the color of the ventilator a bit.

The MK2 version is mounted with screws that holds the ventilator.
The MK3 version just snaps on the ventilator (no