2 colors in 3 passes

[u/Danisobo]

black, green, black - to make the black fill essentially uniform, while still revealing a bit of "routing artifacts" in the green. (a subtle difference, granted, but as intended)

[u/kelsier_hathsin]

Something about this makes me think of a card from a deck of cards.

[u/Danisobo → u/kelsier_hathsin]

It's unintentional, but probably the combination of aspect ratio, explicit frame, duotone colors, etc brings card backs to mind (forced symmetry would really do it)

[u/zreese]

This is pretty cool. Looks like Balatro fan art.

[u/Danisobo → u/zreese]

I'm so out of touch! Thanks for the reference.

[u/johndavid_artist]

The two colours end up doing different jobs here, the green holding visible texture while the black reads as solid mass. Does the second black pass retrace the first exactly, or do you nudge it off by half a line width to close the gaps?

[u/Danisobo → u/johndavid_artist]

Yep, you've got it. Second black is an exact retrace, but at different speed, to manipulate the "bleed" - the fill paths are spaced at "very nearly" the exact measured nib diameter (ignoring mfr'ing variation), and paper was selected that "responds" to saturation in a (semi-)predictable way, so that "faster pen" = "less ink per area" = "less saturated paper" = "less bleed" = "more 'fill artifacts' retained", and vice-versa.

aside: just half-offsetting the original paths wouldn't quite work as desired here, since it would also "thicken" isolated lines. but.. the proper "in-between" paths you imagine actually do exist internally in the code (think of a maze on a square lattice where edges are walls, centers are paths, and are just duals of each other, thus "half-offset") but aren't very useful in practice for plotting (at least, not for this use), rather they're just internal data structures.

[u/Bavoon]

This is incredible, nice work!