Drug paraphernalia can take so many forms. My mother recently expressed concern about having found burnt knives in my younger brother's room. "Don't worry," I said, "That's only from smoking hash."
She also got panicky when she found his home-made water-pipe. She was afraid he had been smoking crack. Apparently she is from a generation before the bong, or she might have known. It is rather mind-boggling to consider the possibilities just for pot-smoking. Here is my list. Please add to it if you like.