Of all of the writing instruments on the planet, these are my favorite. During most of high school, a 2x0 and 3x0 pen were my main writing tools.
Unfortunately I found out that there are some drawbacks to these when taken on an airplane: they tend to empty their ink resevoir onto the user. And the inks these use are... difficult to remove.
I was overjoyed to find that K&E, Koh-I-Noor, Staedtler, and practically anyone else who ever made these still do. Long live the graphic pen!
This was done using a mix of techniques. A total of 54 images were used, taken in two sets of 27 using a CHDK script. Each set was taken at a range of focus values spanning from the very near to the very far. The sharpest part of each shot in the set was combined into a single image using CombineZP, giving this effectively infinite depth of field. The two sets were taken at different exposure settings and the images produced by CombineZP were subsequently processed in Fotomatix as a two-shot HDR stack to help fill in some of the darker shadow areas in the pens.
To the best of my knowledge, this technique of Z-stacking was pioneered by Paul Haeberli while he was at Silicon Graphics. You can read his original article at Grafica Obscura.
(This technique is covered a little better in this article.)