GREEN DAY by Phoenix   How I made my instrument:         I traced the shape of a guitar out of 2 pieces of black Styrofoam.  I taped and glued the pieces together and decorated it. Then I put 6 nails into the top and bottom.  Next, I tied fishing line to the nails tightening each line differently so that there were 6 different pitches. How my instrument makes a sound:         I pluck the strings, the strings vibrate and that makes the sound.