Since posting this Ive been shocked (shocked!) by the number of responses Ive received. Many thanks to all the folks who provided me with the new information. Patricia from Wales was kind enough to send me original insructions and stencils (the RubbaSten sheets) and Roberta from Mission Creek Press provided the technical lesson.

The Menucator (sold by the Lion Duplicator Company of Canadapossibly imported from England) is a portable mimeograph or stencil duplicator. It opens to reveal a screen and palette tray with an extra screen in the lid. The bottom of the box acts as an ink tray with a brayer that locks in.

The RubbaSten sheets were standard mimeograph issuethin tissue that was permeated with wax. A typewriter or steel stylus would move the wax to create the stencil. It was then placed over the blank sheet on the tray with the screen on top. Thick mimeograph ink was then rolled across the screen creating the first copy and adhering the stencil to the screen.