It's like having one of those air deflectors on your vent. The inspiration came from getting a new wood floor and I knew the old rusty metal register we're not going to cut it. I used Elegoo wood PLA. And they work just fine. If you think your furnace heat will melt them, use Pet G or stronger. Also, I changed direction the air was coming out from the original and wow what a difference that makes in the room. It's like having one of those air deflectors on your vent. Now the air is being pushed into the middle of the room instead of up the wall or window. The room is a more even temperature since the old one heated the walls and did not put the air into the middle of the room. It's really made a huge difference in comfort. Plus, the added benefit that it won't rust. I did need to cut it in half so that the whole thing would fit onto my print bed. The left side is just a flipped copy of the right side. Depending upon how beat up your old air chutes are, you may need to sand this a little bit. Or beat your existing register hole back into a rectangular shape. I did. My wife said it was one of the best upgrades to our HVAC system. It's like having one of those air deflectors on your vent.