LED bezel will mount into a ~12mm hole. Diffuser is to be printed using a translucent plastic. LED is either press-fit or glued in place.

Update: added second versions to provide a bit more tolerance (slop). Try printing one of each and see which set works best for you.

Pro Tip - if you find that the fit between the 2 parts is too tight, just increase the X and Y size of the nut in your slicer to be slightly larger ( somewhere around 106 percent should do the trick ).