We have a forced-air HVAC system and two of the registers (the hole where the air comes out) are placed almost directly below outside windows. It's helpful to deflect this air away from the cold window in the winter, so we bought some injection-molded plastic adjustable baffles and those worked fine for a couple years.
Last year both of them broke; one salvageable and the other, not.
Instead of just buying more I decided to design some of my own, since it's more fun for me to make things than to buy things, and since I'm custom designing it they can be made to fit just right.
The basic design is similar to the store-bought models with the difference of being a single piece of plastic and having a complete base instead of having no base on the side where the air comes out. I think both of these changes will make the part a bit stronger than the original.
The other difference is that the new model will be printed in white whereas the original was transparent.
Both are attached to the grate using magnets, but I plan to use somewhat stronger metallic magnets embedded in the printed part as opposed to the flexible kind found on the original unit.
This sort of thing is one of my favorite types of 3D printing, making parts for an old house that fit just right. It's a subset of making parts that no longer/never did exist, and it's beautiful.
Jason J. Gullickson, 2026