In this film i briefly describe types of flexible moulding materials which are as follows:
Gel flex/Vinamould - a hot rubber that sets when cool, this rubber can be re used to make a new mould by reheating, It has less detail than the other flexible moulds and the object being cast needs to take the heat of the rubber which is around 150C
Silicon Rubber - a cold curing rubber that sets by adding a catalyst. This rubber is strong and has great detail. It can be bought in different grades of flexibility. once created the rubber cannot be re made into another shape.
Alginate - This is a material based on seaweed. It has great detail and can be used against skin, though check you are ok first. It sets very fast on mixing 6 minutes for the slow set. It can tear easily and will dry out and crack if not kept damp. Pour any plaster into a Alginate mould as soon as it is made.