Trying to keep a craft-secret today seems pretty futile.
In mostly pre-literate times things were passed down by word of mouth from master to apprentice and keeping other craftsmen from knowing everything you knew made sense that 'knowledge is power'.
When craft guilds came along the secrets weren't so secret except within a given guild. No mason cared how a tanner did what he did and vice versa; but a master mason cared that any journeyman he hired had a certain craft-standard knowledge base and knew how do do certain things.
What matters to most people today isn't the process; but rather the end result. I don't care what you do or how, but will what you make do what you claim it will?
The secret to really good Coq au Vin isn't the wine. It's a really old chicken cooked low and slow. At least in America we seldom see a chicken more than a year old; much too young to make good Coq au Vin.
Trade secrets? Nope, don't have any and don't believe in 'em. If there was some really hard-to-get material, I might sit on a source... though currently I don't have any of those either. What you see is what you get, and if you wanna know how I did something, all you have to do is ask. Geezer
I recall it was quite the work of art despite his limited source material. As a 21st century 'web-hobbiest', my main problem is assimilating a near infinite amount of info, like drinking from a fire hose.
Mac, I do know a craftsman who does have some closely guarded secrets. He is an atlatal and dark maker. He has developed some proprietary method of heat treating wooden and cane darts, and is very closed mouthed about it. I think it is more a personality quirk of his, rather than his fear that a host of dart makers will steal his ideas and market share, though.
i'm not one to withhold any "secrets". i only keep the secret long enough for me to complete the first one and get the kinks out. if i figure out a different way to get something done, i'm more than willing to share. i don't worry about someone making money from what i share, since most of what i do is tedious and time consuming. i know how long it takes and what it costs. if they do it correctly, then sell it for less than i do, they usually won't last long. projects built for the love of it and projects built for profit seldom coexist in one object.