I have used the belly fur for the abdomen, but since the thorax is to be darker and spikier, I think it might be better to NOT blend fur for the thorax, but rather just cut a pinch from the back fur and use that in a dubbing loop for the thorax. I also like black mylar embroidery thread for the ribbing on the abdomen. Is shiny but not too bright, and shows up well against the orangey abdomen.