Organic Fan Guard 120mm

It's the exact shape of a Delta 120mm fan, and should fit any 120mm fan. The thickness forces the air to go straight out, instead of blowing out at the outer edge of the fan. There's nothing near the fan blade to cause extra noise, and it shouldn't restrict airflow at all.
This also matches my 40mm Organic Fan Guard: https://www.thingiverse.com/thing:3160832

I added a screen grab of how I printed them without supports, also if you need the honeycomb mesh thicker you can use "Horizontal Expan