Time to complete: No idea. It was over a year ago. Maybe 2.5 hours.
First I started with a test drawing of the Hatter's head, getting an idea of how I wanted it to look:
Then I did a sketch and started adding in vector layers:
Almost all of the vector layers are in, shown with the bulk of them at 30% opacity:
All of the layers are now in and they have their own color and I've started laying in lines on new layers, grouping the lines to the layer that they are above. I'll show why that's handy in a future video:
And here's the final illustration:
Here's the same image with all of the shapes turned off:
...and with all of the lines turned off; shapes turned on: