Quick version. Haven't had a chance to refine the lines with curves yet because I had to crank this out. But will refine and update when I get a chance. Thanks for the excellent tutorial!
And below here is my second pass, after a lot more sketching and refining. Still have yet to add the subtle curved lines. That'll be next!
And here is an update, with each part of the process done except for the very last step. It's getting close!
Final step, with smoothing the sharp curves: