Far be it from me to argue with Drack, and he's actually totally right about clay and molding to be the preferred method for movie special FX stuff... Only, in the recent years many big studios have expanded to include the digital world, they have 3D printers and even more advanced rapid prototyping systems, and instead of taking body casts they're scanning the actors and sculpt the costumes in Zbrush. No physical materials and the undo ability are very powerful tools - on the one hand they afford much quicker iterations, and on the other hand they help to keep costs down, at least if you have some way to print or rapid prototype your stuff.
Anyway, the point is that these techniques will find their way to the larger public eventually. Autodesk already offers their 123D tools and 3D printers are getting cheaper every day. Even if you can't afford them, there's the Fab Lab movement which basically means public workshops equipped with 3D printers laser cutters etc. that you can use at a small fee, so all this stuff will be affordable in the near future.
On the other hand, sculpting clay with your hands, in the real world, is amazing stuff. Especially for the computer guy I am