Karsten Schmidt (a.k.a. Toxi) was commissioned by PRINT Magazine to create his own generative letterforms for the August 2008 cover. He used the Gray-Scott reaction diffusion model in a Processing sketch (an open source programming language) to generate a 3D typographical model. That 3D file was then printed with a 3D printer and photographed for the cover. You can read a short interview with him at the PRINT Magazine website. In this Flickr set you can find more photos and images of the whole process.

Here is a video of an early Processing sketch, the 2D frames where later stacked to a 3D model.

found at cpluv