I found this art form to be very peaceful, and fun. It became an excellent icebreaker, and we enjoyed getting to know people a little better as they requested specific icons or designs, some of them strategically placed over scars, either to obscure or commemorate.
My favorite experiment of the weekend was a requested "Green Man". Given plenty of time to "play" with teh design, and apply several layers with a paint brush, the results were very much appreciated: