Project X has a lot of book matched parts, and adjacent parts with continuing grain. There are a lot of orientations to keep track of.
I've been using Irwin lumber crayons to help keep track of all of that. And they keep breaking on me. I should know better than to buy things at a home center, but, you know... I was there, I had a need, and like many other regrettable relationships, I gave in, knowing it was really against my better judgment.
At over $1 per crayon, they should hold up better. But for a project like this, using other colors would probably help keep track, too. I'll be using crayola next time. Cheaper, more colors, and more durable. (I think... We'll see.)