When I was young we often made drawings with our fingers smudging a piece of paper. To visualize paper snippets I returned to that technique. To my great deligth, I can add. At times when working digitally I miss getting dirty fingers.
The technique is quite simple: make the edges of pieces of paper black using a soft pencil, charcoal or conté crayon and then rub with your fingers, holding the scrap onto another piece of paper.
Easy does it.