Some days ago I rediscovered my pad of transparent paper. I’d bought it quite some time ago (I actually cannot remember when), and I’d never done anything with it.
Now I use it to work on my sketches and drawings. First I make a rough and loose sketch on some old paper, and then I put on transparent paper and clean it up. I had one rough sketch for the two faces above, and it was fun drawing two quite different faces out of it.