metal, I worked with a guy in the car business who only had one pipe. The stem was chewed through, the cake was probably 2 nickles worth and he smoked nothing but Borkum Riff Whiskey in it. He was old school and I used to ask him why didn't he get a new pipe or even have a few. He looked at me like I was crazy and he said until his pipe completely falls apart, he won't buy a new one. We were both managers so we were equal in regards to our positions. I took some pot and put it in his pipe while he wasn't looking. You should have seen his face when he started smoking it. He had no idea what it was, but he knew something wasn't right. Me and the salesmen were laughing our asses off and he swore at us up and down, telling us what assholes were. He dumped out the bowl, loaded it back up with BR and never left his pipe unattended again.
He finally cracked the stem so bad he had to get a new pipe. I am not sure what pipe he replaced it with, but it was fairly large. I was a cigar smoker at the time but when I did get into pipes, I swore I would never be a pipe smoker like he was.