For me, this is the traditional way of drawing Shattuck. As an alternative, it could be done with straight lines, instead of curved. I do it both ways, depending on what I am working on.
Zentangle drawn on black, Strathmore, Artagain paper using a white, Sakura, gel pen. Shading done with Copic Markers and black colored pencil. Highlighting done with General’s Charcoal White.