Nob for 3/4" hex nut

This file is for a ¾" hex nut, modeled with 0 tolerance for a really tight fit, so you may want to scale it up depending on your specific use case. In theory, this can be used for various sizes, but you'll need to scale them accordingly. As for material and settings, use whatever suits your needs. I used PLA and low infill since it's not under heavy load. Print hex side down, didn't do that on mine and looks horrible, cant be bother to remake it though. Points if you know what machine its on. 

I included a STEP file so modifications should be quite easy.