Gina of clutter punk says,
Recently I’ve done a little free motion machine embroidery, or thread sketching. From some of the comments I received it’s clear that this seems all a bit fancy, mysterious and only for extreme sewists. It’s not. So I’ve written this post to demystify the process of ‘thread sketching’, and hopefully some of you will be encouraged to give it a go.
Her thorough and well-illustrated tutorial is a great introduction to this technique. See the tute.
And many thanks to kath_red of whip up for pointing out this great post.