What a fun concept! Start by sketching the chord symbols in a bold black line—think of G‑major as a fat, solid stroke, maybe 3‑pixel width if you’re digitizing. Then for the minor seventh, soften the edge: a thinner line, maybe 1‑pixel, but add a feathered cross‑hatch on the inside to give it that “soft” feel. Keep every hatch perpendicular to the main line, use a light stroke density so the shape stays clear. Remember: no gradients, no blur, just straight edges and deliberate hatching. It’s like turning music into a comic panel—each note a distinct, expressive line. Enjoy the process, and let those little imperfections tell the story!