I've been watching the Man at Arms series on Youtube lately and forging a weapon seems like a lot of work even with modern technology. How did blacksmiths do it back in the good old days before heat treating furnaces and all that heavy machinery? Were the products of poor quality? Were only a small group of people in charge of the forging during times of need? Other insights are much appreciated!
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They organised in factories and had some basic management organisation. The fabricae in Rome and China had production line. Check out lamellar and see how easy it is to mass produce and make modular. A favourite in eastern armies and basically made scale obsolete once access to the techniques were widespread. Sorry I don't have any sources since I picked it up here in there, but I do remember reading about production lines in armoury forums in both China and Roman empires (you will know them by the uniformity and standardisation). Also check out evolution of Chinese armour in YouTube.
I'm not sure what you mean by "ancient" but I answered this question yesterday with regard to Europe in the 14th-17th centuries:
http://www.reddit.com/r/AskHistorians/comments/2c1kl3/how_was_plate_armour_made/
Basically there were a few cities that were centers of arms production. These cities had large numbers of workshops that worked with each other to make arms in an assembly line style. A lot of the tasks associated with arms production, such as smelting, hammering, polishing, etc. were mechanized. Water-wheels provided power for bellows, hammers, and grindstones. Sorry, I do not have the knowledge to comment on other time periods or cultures.