John in NM
I doubt those were ever made by hand. I've drilled holes like that before, so you could do it with a brace if you used a really big chunk of wood and then cut the barrel channel to match.

In a factory, a lot of those long cuts are made with something similar to a horizontal mill - that is how I would do the barrel channel on that piece for example, gang together about 6 cutters with spacers on a long arbor and do 6x at once. But that round hole has to be done with something like a router or perhaps they did drill it. I'll look closely at one when I get back to the shop (likely a couple weeks) and see what I can tell from tool marks.