I know a similar effect can be achieved with the oil brush and eraser, but it would be very interesting if the next version of AR had a scratchboard option!
In real-life media, the sketch is put onto tracing paper and the silhouette of the picture is traced onto a chalk-covered board. the silhouette is then brushed solid black with india ink (parts not needed are left white) and the artist uses the traced sketch to scratch the details in with any varying type of sharp tool.
this would be most interesting to use digitally, and the step of tracing paper is already covered.