I’m impressed with John Paul “Laken” Olivares’ line drawings. He uses metallic gel pens on the reverse side of an illustration board. And it takes him “around four to eight hours, and that is just the drawing time. It will take longer, if you include the meditations before a visionary work or a mandala,”  states Olivares.
1. Lakandiwa. "Answers to some questions regarding my art." Deviantart.com. July 17th, 2011. Artwork © John Paul Olivares Link via Art Sponge