This is a video about the diode, in this case a Schottky diode made with a coil of copper wire filed to a fine point touching a piece of galena sitting loose in a bottlecap found by the side of the road.

The video is notable for demonstrating the original "breadboard" technique, where you connect your wires and components by clamping them to a wooden board with the head of a wood screw. The book I learned the technique from recommended using a dished washer under the head of the screw so that the screw head doesn't push the wires sideways as you tighten it.