So I picked up this warg rider super cheap in an eBay lot. He was missing his right arm and the warg was missing two legs. Initially, I was thinking I could cannibalize a leg from a plastic horse or something and just give it warg-fur with greenstuff, but then I thought I'd try sculpting new legs entirely for the beast. I think it was pretty successful for a first attempt.
So here's the rider's arm transplant first. Nothing difficult; just pinned a WHFB Skaven halberd arm on, and shaved it down to remove the unsightly body hair. It matches ok, i think.
To sculpt the legs, I first pinned 1mm wire into each leg socket to act as an armature (to give the sculpt structural support). I looked at the other wargs I own, and used them as a visual reference for bending each wire in the shape of a warg leg. I used round pliers for this.
Then I put greenstuff on each leg to build up the muscles. After I was happy with the rough outline, I left the greenstuff overnight to cure properly. This is important for the next stage: putting the fur on. This way, the underlying muscle shape is set, and I won't ruin my previous work by accidentally smooshing up the soft greenstuff when I'm doing the fur.
So here's the fur. I put on a thin layer of greenstuff over the muscle layer, and just used a blunt old Exacto blade to etch in the fur details. I just tried to make it look natural.
And here's how he looks next to his undamaged warg-riding buddy. The whole project came out better and was far easier than I expected. C&C most welcome!