The air diverter housings beneath most of my floor registers broke at the tabs where they connect to the metal grate. I designed this replacement, which fits many of the standard 10" x 4" models, and should allow for reuse of the original diverters and slider. I also designed a replacement slider (uploaded separately), as the originals often broke as well. The model just fits on the bed of P1 and X1 printers without special setup, and will print without supports (some minor cleanup of bridges required).

I can't guarantee exactly which makes/models this fits - only that it worked for several of the different registers in my home.