You saw multiple examples? Where and when did that take place?
Kind of surprising that no one had ever heard of one much less seen one until I brought this one to the shop. This had to have been 20 years ago I would think. Like the article said, it wasn't 100%, but all believed it to be shop work.
This knife was probably circa 1955-56.
I will add that I have seen a couple with wood, not something the shop would have and on later knives, and they were awful. Could have done a better job in jr high shop class and I sucked.