vent cover

This is for fume extraction for a 4 inch hose exhaust. It was used to vent my 3d printer enclosure. It prevents back draft into the enclosure if there are strong winds. The lid is very light weight and all that is needed for the hinge is a 1.75mm piece of filament. You can just melt the ends of the filament and it will keep it from sliding out. Doesn't require much pressure to push open the lid as it's only 1mm thick. I am currently using a 24V 60mmX15mm fan and it does well. The square design for the flap is to help block rain from getting into the hole. There are 4 screw holes that will fit M3 screws if you want to screw it onto something as seen in the attached photos. The vent opening will work just fine for a 3 inch opening as well with no issues. The vent flap will require minor supports just for the hinges.

Also added webbed version to keep critters out if you need it.