- Cardboard milk carton (half-gallon size)
- Sharp knife
- 45-inch length of nylon fishing line
- Tape shut the top of a clean, empty half-gallon milk carton.
- With a sharp knife, cut vertical slits, big enough to slip a yardstick through, in two sides of the carton, two-thirds up from the bottom.
- Cut a notch about a half inch deep near each end of the yardstick with a saw and insert through the carton.
- Position the carton near the center of the yardstick. Make a loop in one end of the length of fishing line and slip it over the notch on the top of the yardstick.
- Pull the line over the top of the carton and loop it around the notch at the other end of the yardstick.
- Tie securely and pull the carton to one end of the yardstick.
- To play the guitar, strum the string near the top edge of the milk carton with one hand. Pinch the string to the yardstick with the other hand to change pitches.