While fixing up the wiki articles on the two Diablo III design panels from Blizzcon, I put together a few images collecting the step-by-step design concepts of the Archer and Demon Hunter.
As described in the Gameplay panel article, the developers knew they wanted to include an archer class right from the start, but it took a long time to settle on the final character design. They experimented with a variety of rangers and trackers and woodland bow-using type chars, but they were moving away from a ranged attacker style, and the devs thought they were all too traditional in their design. The concept didn’t have that “twist” the devs like to put on the Diablo III characters.
Even after they arrived at the idea of a Demon Hunter they still had a lot to different ideas and versions to work through; for a time the character was huge and demonic, then had just a demonic arm, before being scaled back to a more human final product. Images showing the steps in these design processes are collected below, and if you want more detail than this very quick summary, look at the panel article for a full transcript, dozens more images, and videos of the panel.