This was about forty years ago, so I've forgotten a lot of the details. I do recall that there was a mixture of machine tools, jigs, and hand-work. The center holes were bored using a gun drill on a lathe, using compressed air instead of oil to clear the chips. The taper of the bores was then added using custom reamers. The final tuning adjustments were done by undercutting the finger holes by hand. I sold most of them by mail, to customers as far away as Europe and Japan. Most of the recorders I made were based on an ornately carved alto recorder that was made by Oberlender in the 18th century. The man I learned the trade from bought one of mine and had it carved like the original.
I was rather surprised to discover an ad for one of mine, offered at a price that is at least three times what I charged for it! Such is inflation over the course of 45 years, I guess!
https://earlymusicshop.com/products...r-oberlender-in-boxwood-a415-previously-owned
I also ran across a YouTube video on recorder making, by the Von Huene Workshop, which is where I learned the trade. I haven't watched it yet, but I'm sure it will bring back memories.
After I moved to California, I collaborated for a while with Charles Collier, a maker of Renassance recorders of all sizes.
I was hoping to make baroque bassoons and dulcians (the latter being the Renaissance precursor to the bassoon), and at one point I toured museums in Europe to study examples to copy. I got as far as drilling the initial long holes in some blocks of maple before I ran out of steam.