A bundle of 3 of these is for sale on eBay, item 220085946649. From the pictures, these are the "single helix" variety, with one thread running around the axle. There was also a double-helix version, as Box Freitas and I discovered a few years ago. This looks like a much coarser thread, but when you look carefully, there are actually two threads running around, not one. The two designs require two different "acorn" assemblies, the female part.
If you happen to need a double instead of a single, I had three made a few years ago, reproductions based on an original I borrowed from Eric Elman (Thanks!). One is left over, and I would sell it at cost, $75.
The skewers are interesting in their own right, with lots of little machining operations. I don't remember the threadings, but the handle end has two threading operations (including a LF locknut), then there is a sort of Acme at the business end, and a pair of flats for assembly. I think the skewer diameter changes at some point, too. My machinist friend wound up making a rod clamp/jig so he could start the two threadings accurately -- not a problem with making a single. I still have that, if anyone wants to make more of these doubles.
harvey sachs
mcLean Va.