Drawing Techniques: a Guide
Dry Media: Stylus  
The stylus, a pointed metal rod used since antiquity to draw or write on wax tablets, acquired a more specialized function after the introduction of paper. Since it impressed a barely visible line into the surface of unprepared paper, it was useful for underdrawing, that is, laying down the initial thought to be built up with chalk or pen, for tracing, for laying in perspective lines, or for squaring for transfer.  
Dry Media