Sometimes simple is lovely—this hat is constructed in a basic rib stitch using two strands of fingering yarn, so marling is very easy to achieve. I used two strands of marled yarn in the same colorway, so I didn't take advantage, but I'm still very happy with the FO.
Pattern: Morning Walk hat by Monarch Knitting, size large. Knit in Woolfolk Sno 01+15
Lessons: Woolfolk Sno has a bit of a halo, so knitting marled fabric causes the halo to blend into a soft grey that mutes black/white yarn. I don't mind the effect, but it's something to note if the goal is a crisp black and white marled fabric, another choice of yarn might be more appropriate.