This is a bracket that I used to mount the external WiFi antenna (SMA) to my Ender 3
The antenna is for my ESP3D setup and is plugged into a Wemos D1 Mini Pro that is installed in the mainboard cavity.
Print in orientation as shown to provide maximum strength for the clamping part.
The clip itself is quite a tight fit, which is good since you don't want the antenna to move.
It is loose enough to slide.