if you thin the brush down to 1xwhatever number, then rotate it round you can see on the monitor it will split into 3 or 4 lines, draw with that and you get the multi line effect....
It's a caligraphy effect with the pen Hide. At a certain angle you get multiple lines, as Chris shows here. Fascinating stuff. Doesn't work as well with the airbrush though. You should try with the square brush next time Chris.
drawn in 18 min
Keep it up!
Nice effect Chris, if does look likeyour patterns.