Very simple remix of the Ender 3 Power Supply Fan Silencer by [Eigengrow] (https://www.thingiverse.com/Eigengrow/about) so that it fits the Ender 3 Pro Meanwell power supply. I printed off a few layers from his original design to check the size, and it worked, but had to be flipped since the Meanwell PSU screws are oriented differently than the original Ender 3 PSU. Used tinkercad to flip the design and printed it off with the channels facing up to minimize how many supports were needed and it fit just fine. Redirects the air toward the back instead of off to the side and reduces the noise pretty well without significantly impeding airflow.
Just like in the Eigengrow's version, the holes are undersized for the fan screws, but that means you can carefully drill them out to fit (I was able do so by hand, just twisting a bit between my fingers). Unscrew one screw from the fan, fit the part and screw it in just a little loose. Then unscrew the other fan screw, rotate part up to place and screw it in, tighten up the first screw.