Carbon Electrodes: the carbon electrode from an old #6 dry cell. Carbon Rod: 2 length of lead from a wooden pencil. Electrode Base: wood, 2 long by 3/4 thick (width doesnt matter). Sounding Board: cigar box (cover not needed). Mike Base: wood, 7 by 9 by 3/4. Battery: 6 volts. Headphone: the same ones used for the crystal radio experiment. Minor Items: 6 screws, 4 nails, 2 Fahnestock spring clips, hook-upwire.
FORMING THE ELECTRODES. Start by removing the 1 diameter carbon electrode from the dry cell. Bust it open with a hammer and chisel. Clean the bottom of the electrode, and saw off a 1-1/2 segment. Then saw the segment in half lengthwise, giving us two half-cylinder electrodes. You might want to file or sand the rough surfaces a bit.