1/2" Bolt Knob. (1/2" bolt dia size that uses a 3/4" wrench)

This is a knob for a 1/2" (.5") dia bolt. That means the hole is 1/2" and the hex is sized for a 3/4" head for a 3/4" SAE wrench. It is designed to drop over the bolt so that it doesn't need glued to the bolt. And unlike if it was glued on, it can't come off. It could still be glued if you wanted... or a back side nut could be added. That said, it fits fairly tight as it is so it all depends on the use case.
I used Elegoo PLA-CF for the one in the photos. I'm using Elegoo Rapid PETG for the next run and will upload the 3MF for that.