Graphic Artists Guild
The purpose of the Graphic Artists Guild is to promote and protect the social, economic and professional interests of its members. The Guild is committed to improving conditions for all graphic artists (including, but not limited to: animators, cartoonists, designers, illustrators, and digital artists) and raising standards for the entire industry. The Guild embraces graphic artists at all skill levels.
I've been using Koh-I-Noor Rapidograph Technical Pens since 1969. My aunt bought me my first set when I was 12 and I have used them daily ever since. I love the fact that I can mix my ink colors to match my watercolor or my wardrobe and use "Pelikan Drawing Ink A" almost exclusively. Though the inks made by Koh-I-Noor and Winsor Newton are satisfactory.
If you are a beginner, I would NOT recommend purchasing anything smaller than an 0 (0.35 mm). Even as a professional I find cleaning a 4x0 to be a challenge. I work most often with a 2x0, and find them to produce the smoothest flow, if kept clean.