So, I know where you're supposed to go to get it, the cooky doctor guy in Diamond City. But after you do the quest for Nick, and the doctor goes loopy and you kill him/he kills himself, where are you supposed to go to get tattoos and stuff? Can you just not get that stuff anymore now that he's dead? I wasn't really going to do anything like that, I was just curious since he's gone now.

You can build a plastic surgery stand in your settlements I think and assign a random settler to it.

I found out the doctor guy just takes over after you kill the other doctor, so that answers that question.