According to Smith in his seminal work, How to Do Nothing with Nobody All Alone by Yourself, W. W. Norton & Company, 1958:

"The helicopters we made weren't really helicopters.  They just looked something like what we now know as helicopters.  They were made from a piece of paper, and they worked very much the same way as the maple wings I told you about when I was telling about polly-noses."

I'm not going to describe polly-noses here.  You will have to find a copy of his book for that.

Specs:

The helicopter is printed on 32 lb. text stock (7 3/4" x 2 1/8") from Paper Access.

"HELICOPTER" was printed with 12 line (2" high) wood type.  (I don't know the manufacturer or the name of the face.)  The instructions on the back are printed with Colwell Handletter, ATF foundry type.

The image of the paper helicopter is a copper die from Owosso Graphic Arts.