I have been playing around with Instamold (bought a single stick for £2 from Bitzbox.co.uk) and been quite pleased with the results.
Covered the ribs on my nightmare teddies that I didn't like by molding some fur, cutting back the ribs and filling with greenstuff and then pressing the mold onto it, then blended the edges with scuplting tools.
I also cast a hat from a Austringer and added to Miss Demenour, think I need to recast and tweak, but you get the idea, What do you think?
Leigh