Well, the reamers I think we used (mom was a professional artist and used one) are tapered, and are hardened tool steel, like a similar rasp, or flat file, and with a classic, file type wood handle. In the case of the reamer, it was overkill for the materials it was used on (wood frames occasionally soft steel frames), and it would have lasted a thousand years at a minimum, unless killed by rust.
In my experience even tiny 60-80 drill bits work well enough on plastics like Delrin and ABS, but I could see where you might want something beefier if you are working on soft metals. In which case you would also want a file card (cleaning card).
But HOW? Well a tool like that would probably be machined on a fine scale lathe or milling machine like those from Sherline. And then maybe heat hardened if need be (a process I am only barely familiar with at best)
Otherwise, I might look at modifying simple high speed metal drill bits. There are various types, and made out of various materials, up to and including cobalt steels and titanium.
And at this point, I'll recommend you look at how to modify materials like those yourself. I've just gone in over my depth, but for a slight bit of experience with Titanium golf shaft to club head assembly. Cobalt steels are well above my pay grade.
