This is something I've done a bit of over the years. I just did this one of Andy Irons, one of my favourite surfers, who tragically died a couple of months ago. I do these using black textas, methylated spirits and cotton buds. The board is mine, a custom by a good mate of mine and awesome shaper Stuart Paterson from :pcc surfboards. I thought I'd dig out some of my older ones and post them now.