Yes, I guess I meant Z! I'm used to 3D animation/modeling where Y is up and XZ is the horizontal plane. I'm imagining something similar to a Wacom tablet with pressure sensitivity. So a line can start out one thickness, then get thicker and thinner over the length of the line to create more of a hand-drawn look. This is way beyond my ability, but just wanted to throw it out there hoping to inspire someone with the know-how.