I needed a vent for my 3d printer enclosure and didn't want to buy a window kit becuase I had spare wood to make a nicer looking window vent kit. Also, most window kits are 4 inch and my enclsoures vent ductwork is 3 inch so I whipped up a model that would work for my situation. The front is a grid pattern that is pretty small so it should allow air flow but prevent any unwatned guests in the home except for maybe gnats if they can overcome the airflow out from your fan. The grid goes the full length of the “block” portion of the vent so its pretty deep and sturdy. I printed mine in polymaker HT-PLA so that it could have a better chance of withstanding summer heat where Ilive. Depending on your climate that may not be necessary but you can print it in whatever material works for your purpose.