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Copper Rule
(i.imgur.com)
Be sure to follow the rule before you head out.
Rule: You must post before you leave.
They found and translated a bunch of tablets of letters to him that were found all together. As I remember, there were several complaints about the quality of the copper and they decided the building they were found in must have been his workshop. It's possible he has happy customers who just didn't write him letters.
The internet has shown that there will always be someone complaining.