Nothing new
In the seventies there was the "Revolutionary's Cookbook" a book that got some notoriety instructing how to make bombs. molotov cocktails, poisons etc. It was mostly leftwing then; the SLA, the antiwar flower children and of course the odd right-wing nut group.
The lefties have always been more dangerous but it's encouraging that the domestic lunatic fringe, right and left are still just a fringe after all these years.