At some point in your life someone may have told you that a metal lathe is unnecessary, you can do the same thing with a power drill and a file. More than likely this person was an old man and you chucked up the comment to ignorance or dementia, I know that’s what I always did. Apparently that old guy isn’t crazy after all.
Recently I developed a need for a 9 mm fine thread bolt. Now you may or may not be aware that even size metric bolts are widely available but the odd sizes are very, very rare. I’m not sure why this is, probably a manufacturing conspiracy, but I’ll rant about that another time.
The solution is simple, Acquire the next size up, 10 mm in my case, Long enough to have no thread over the length I need to install my thread. Reduce the diameter, cut to length, and run a die over it. Bob’s your uncle.
This bolt is going to replace the handle in my tripod head, on occasions when the handle is in the way.