I've now reached the stage where I have a virtually finished ready-to-use Spitting Image stylee puppet head of Nasty Nick Griffin, so I thought it might help other bumbling amateurs like myself if I show how I got to that stage. But before doing so, you should take a look at this video which shows the construction of a very similar type of puppet (Karius and Baktus) by make-up wizard Lars Carlsson. I found it invaluable, along with various websites linked to during the next few posts.
First, the clay sculpture. You've seen it juxtaposed with the man himself in the previous post, so here are three more views of it. This is the finished item, made from the cheapest water-based pottery clay - literally the stuff they dig out of the ground. As I live in London, I buy mine from Alec Tiranti Ltd., a superb sculptors' supply shop on Warren Street. It's cheapest if you buy the 25kg block but, fuck me, you risk your back getting it home on the tube...
As the stuff dries in air (well, the surface does, leading to cracking), it's generally advisd by Those In The Know that you sculpt quickly. Fortunately, as it took three days or so for me to sculpt it, Those In The Know also point out that you can keep it from drying by wrapping it in polythene whenever you take a long break from working on it. I would simply put a large carrier bag over it, sealed at the bottom with a rubber band. I should imagine giving it the odd light mist with a fine water spray would help.
I'm not sure how much useful advice I can give about how to sculpt - I started with a wooden stick mounted on a base, I then bulked out the stick with wire and newspaper and masking tape to make a crude 'skull' or armature onto which to apply the clay. This serves to anchor the clay, keeping it from slipping down the stick, and saves on clay. Start off roughing the gross shapes, getting the proportions right, adding detail later. Have a good browse of this forum for some great advice and to see some excellent work.
In terms of the design, if I was sculpting him again I'd give him a much fatter, bulkier neck and take in the forehead a bit, also making it squarer. I would also make a smaller scale maquette first to get the overall look and proportions right, before committing to full-size clay, but hey-ho, I'm fairly happy with it for a first attempt.