It's very much part of the history of the air gun that the production of simple outside lock airgun was within the means of any good village mechanic. None of the regular gun-making skills are required.
If you ever want another challenge, you might want to take a look at the Bourgeoys’ Airgun design, which is widely credited as being the earliest of all known pneumatic designs. I think it is a brilliant design and, as far as I know, has never ever been reproduced. I started a thread about it some time back on this forum. One of the real nice thing is that, unlike just about every other early airgun designer, we have a picture of Bourgeoys. https://en.wikipedia.org/wiki/Marin_le_Bourgeoys