Let us all hail the great American tradition of amateur inventors, personified today by the forgotten Herb Bartlett, whose love for hovercraft extended to making his plans available to the youth of the USA, contacted through his ad in Boys' Life magazine
This image is found on the photo archives of Life magazine under the title above. I cannot discover any accompanying article to explain what this device is. Your best guess?
Category: Explosives, Geeks, Nerds and Pointdexters, Mad Scientists, Evil Geniuses, Insane Villains, Movies, Robots