Assemble your parts and tools. Place the plugboard on a flat surface and place the wiring schematic next to it for easy reference.
Follow the wiring schematic carefully. Each large black dot on the schematic represents a place where you plug a wire into the plugboard. Connect the ground wire to the 555 timer and plug into the plugboard's ground plane. Connect wires 2, 3, 4, 6, 7 and 8 (as marked in the diagram) to the 555 timer and plug them into the plugboard. Connect wires to the 1K ohm resistors and plug them in as shown in the diagram. Connect the 22 uF capacitors and plug into the plugboard as shown in the diagram. Twist together the wires for wire 6 and one 22 uF capacitor and wire 3 and the other 22 uF capacitor and plug them into the plugboard. Connect wires from the ohm resistors to the positive and negative poles on the plugboard. Connect the speaker to the negative wire and the second (rightmost on the diagram) 22 uF capacitor. Connect the 250K Ohm Potentiometer (knob) to wires 6 and 7. Complete the ground wiring. Attach the 9v battery snap-on connector to the positive wire and connect the battery.
Test the metronome by attaching the battery and adjusting the speed with the knob. If it doesn't work, check all of the connections and make sure that you've attached the elements using the correct polarity.
Glue the elements to the plugboard to make the metronome more stable.