For instance, who made stone moulds used to cast pewter and perhaps bronze items? Having had a skim through several sources of information about stone moulds, such as the Museum of London books, the Historical Metallurgy Society journals and excavation reports, I can’t find anything about this question. Of course being a proper careful archaeologist you can’t go beyond what the artefacts tell you, and they mostly don’t come with labels or engravings saying “Made by Bob”.
Obviously carving stone is a specific skill associated with masons, but the moulds are quite small and were probably carved using small sharp tools and files. My experience of making them suggests that with a modicum of artistic ability and fine motor skills you can carve moulds reasonably well, but the complex ones for pewter badges will take quite a lot more practise and real artistic skill.
Which therefore does not mean a stone mason is required.
One suggestion, in “English Medieval Industries” (page 78 of the paperback edition) is that many of the more detailed pewter badges were cast in metal moulds, the metal being cut by seal engravers. Who would indeed have the requisite skills, but I would need more evidence that they actually used metal moulds for this sort of thing in the first place, given the stone moulds that we know of from Britain and Germany, and the fine detail you can get in any fine grained rock.
I did read somewhere that the earthen moulds for casting bells and cauldrons and suchlike in, were made by a specialist on making them, referring to some records from medieval York, but those were single use moulds and he would have made scores every year, whereas a good stone mould can make 300 or 400 pewter castings and thus last for years of use.
Certainly engraving metal moulds would be harder for foundrymen to learn and do than simply outsourcing the work to someone else, but on the other hand they might, especially in smaller towns, encompass engraving within their skill set, as it is in a way related to the finishing of small items.
Turning to “A History of British Pewter”, we find mention of moulds in wills, but unfortunately it does not say what the moulds are made of. Some will be bronze, for plates and the like, and maybe they all are, or maybe some are stone. The authors write that metal moulds were widespread in England in the 15th century, attested to by references in the London Pewterer’s records, in Welch, i, 14-15, 105, 120, 175, 179. Welch is “History of the Worshipful Company of Pewterers of the City of London, 2 vols, 1902. (Note to self, the NLS and St Andrews and Glasgow have it) They also assume that the pewterer would make his own moulds. It would be comparatively simple for a pewterer to cast their own moulds (Or got a foundry to do it, but in smaller towns they were often both the same person and workplace), and spend time finishing them off. It would certainly negate the need for an engraver.
In fact, having been spurred on by this question to read more, I have an answer in the book “Pilgrim souvenirs and secular badges” by Brian Spencer, one of the Museum of London books. It says in the introduction that “Little is known about the men who made the moulds, an operation that called for skill in small-scale precision work as well as a degree of artistry and iconographical knowledge.” It seems some records in York and Cneterbury mention mouldmakers, i.e. people who carved the moulds, whether stone or also, as is shown in the book, cuttlefish bone, but it is not always clear in the records whether they made their own mould or hired them. The introduction also mentions the use of seal engravers in mould cutting and goldsmiths and that bronze moulds for casting pilgrim souvenirs are also described.
So we have more of an answer than at the start of this post. With any luck there is more information available; I shall certainly be chasing up the excavation reports of the moulds mentioned in the book. Cuttlefish bone is one substance I haven’t really looked at, but will surely be the subject of a blog post in the future.