I love the idea of a crystal set radio built into a pencil, as illustrated in this September, 1939 issue of Modern Mechanix. It reminds me of the clandestine radio built into the water bottles in James Clavell's kick-ass WWII novel King Rat.
A MIDGET crystal set, built into a common lead pencil, is the technician's answer to demands for a personalized radio receiver. The crystal and cat's whisker are built into eraser end of pencil. Headphones complete the outfit. Construction plans for a similar device were carried in the May issue of this magazine.
