I encourage you to click on the photo above and see it at full size. This is not a source for how real 16th century armour was made (and an expert tells me that its not a very good replica), but how Daniel Tachaux made a replica during the First World War.
Students of the armour of the 15th century tell each other about the wicked deeds of Bashford Dean, curator of the Metropolitan Museum of Art and armour collector who kept an armourer on staff. Details and sources can get a bit sketchy. Fortunately, the Met quietly shares photos of the kind of work which D. Tachaux was ordered to perform on surviving armour from archaeological sites and neglected collections:
As you can see, Dean’s idea of restoration was more like turning a heap of scrap back into a 1957 Chevy than the kind of careful limiting-of-damage which curators perform today! Fortunately, I have never heard that he restored any ancient armour.
Edit 2023-03-24: block editor. See also “Adam Savage Baffled by Obscure Armor-Making Tools!” (2023) https://www.youtube.com/watch?v=6F643XUqJ-o