This is up there with Claude Paillard creating early 1920s-style triode vacuum tubes entirely by hand in his home workshop:

Chris from Clickspring is building a skeleton clock from scratch using a home machinist’s shop, and documenting it in lavish, hypnotic detail in his Youtube channel.

via Watch: a home machinist makes a clock from scratch, right down to the screws and washers / Boing Boing.