Pen 1 draws the outlines, pen 2 the tone lines, pen 3 the hatching. Heavy outlines go over each one three times; load a thicker pen 1 to push the lineweights further.

Pen 1 is the dark ink for the shadows, pen 2 the light ink for highlights and midtones. Where they overlap you get the mix. Pick the inks under Colours.

Nothing is traced: the picture tunes how each crystal grows. Flurry drops flakes on the strongest edges first, so they follow the outline of what the camera sees; each flake is grown from its own patch of the picture. Bigger flakes sit on strong edges in dark areas.

A needle etching: tone is built from little groups of parallel strokes, each at its own angle, stacking up in the shadows and leaving the light almost bare. Pen 1 outlines, pen 2 light hatching, curls and flicks, pen 3 the deep shadows. Hatch wobble makes the strokes looser.

Hatch

Lines

Flow hatch wraps round the forms, Rigid keeps an engraver's straight diagonal, Facets cuts the sheet into shards each hatched its own way. Lines thin out and end as the tone lightens; cross-hatch builds up in the shadows. Pen 1 outlines, pen 2 hatch and dots, pen 3 cross-hatch. Shading pushes the hatching lighter or darker.

Outlines go on pen 1 and the fill on pen 2, so you can plot them in two colours.

Cell fill

Outlines stay on pen 1 and the fill goes on pen 2 (pen 3 for Subdiv), so you can plot it in two colours. Darker cells get tighter fills, and Cross, Grid and Iso add directions as the tone deepens.

Lines that pile up at the point can saturate the paper. Thin zone sets how far from the point strokes are staggered to a stop, so the line count there stays even; Lines reaching point is the share that still run all the way in.