For a no-color print book it can be complicated to find proper gray tones in a multi-function plot to distinguish the curves. One can use different types of gray or dashing, and to some degree it works well. I'm wondering if one could use the new MaterialShading in PlotStyle somehow. I'm thinking along the lines of perhaps a ton of tiny spheres in different metal colors, possibly with overlap. Maybe silvery tones, coppery tones, or texture materials (would have to experiment a lot with this) could provide good contrast when printed in b&w or grayscale.
I realize materials make only sense on 3d solids, but can we contort that somehow for line plots?