This took all day.
It's not freehand. I found the pattern I wanted on the internet, printed it out at the size I wanted the tiles to be, taped it to the top of my base, and then went over the lines with a pen to press the pattern into the top of the base. Then it was just a matter of painting the colors within the shapes that were etched into the surface.
I'm concerned that it's going to be too busy and draw attention away from the figure, so I may go back and cover over the yellow with dark brown or something. That should dull it down some.