When you stroke the bow across the string it vibrates and causes the violin to make sound. When you play a different string it changes the pitch. When you also place your fingers on different spots on the string you wish to change the pitch on, it changes the note, which also changes the pitch. I think I am going to use wood but I am not sure yet. I will play my instrument using a bow. My plan is to just take my time and not to rush so I don't mess up building it. My outstanding questions are is there any material that we can't use?