Fifty years ago, the September 1969 issue of Electronics Illustrated showed how to put together this greeting card radio. The chasis was a 6×9 inch greeting card. On the left side is a homemade circuit board consisting of aluminum foil attached to cardboard with rubber cement. The top half of the circuit board is also the stator of the variable capacitor, with the rotor being another piece of foil cemented to cardboard. The crystal earphone was permanently attached, presumably meaning that extra postage was required.

If the idea looks familiar, it’s because we’ve featured similar ideas in the past, such as this 1947 one-tube set or this 1940 postcard radio.  If you’re looking for parts, see our crystal set parts page.