Apply random lines, scribbles and splashes. And aim to move your whole arm, perhaps even your whole body, to help you loosen up. Water-reactive crayons or pens, or the best watercolour pencils are ...

Sometimes, though, you might just want to do some freehand pen-and-ink drawing using such "captured colors." That's just what Scribble's upcoming Ink color picker pen is designed to let you do.