I remember seeing this figure posted to various painting sites way back in 2003... part of the Rackham craze that had a major effect on sculpting and painting.
While today's big change in sculpting is ZBrush, at this time using additional materials that were not green stuff for sculpting was not very common. I believe that Fimo was also used, which probably led to lots of exploding originals during vulcanization.
Having done a lot of stuff with sculpey, I know that you can get really fine details with it... and it can even be carved and sanded after the fact.
I believe that I used some Fimo as I was sculpting this giant Mastadon:
It was very fun to get a chance to work on this figure myself, as I can still remember some of those pictures that I saw posted in the days of painting forums. Almost past living memory! :-)