It takes a while to render but my mould master openscad library can make masters for quite complicated objects.

These came out pretty well but I'm going to invest in a syringe to make sure I get chocolate in to the nose and ears next time.

The silicone I used was the medium hardness one from:
http://www.dwrplastics.com/product-information/538a068b9ed12/RTV-Addition-Platinum-Cure-Food-Skin-SafeSilicone-Mould-Making-Rubber-1kg-kit