What are the most tricky things you have to deal with on a day-to-day basis?

It�s a challenge because it�s never straightforward. Each episode has its own challenges. We used to say �problems� but we decided we were using that word too much.

Some episodes, for instance, can be very heavy CGI (computer-generated images). We�ve done episodes that cost over two hundred thousand dollars just CGI.

Other episodes are very heavy in prosthetics - the designing of the prosthetics, the sculpting of them and the making of them. It�s not just a question of making one thing. If you�ve got a principal [actor] and then you�ve got a stunt man who doubles him and then maybe they work four days� You start multiplying this with the number of prosthetics that you actually need and it can become huge.

Also, you then get into a tremendous number of make-up guys. We�ve had as many as 44 make-up people on an episode. Two episodes ago (Bargaining parts one and two) we had ten demons fighting with the Scooby gang, which is seven people. So, there�s 17 principles and each of them has a double, so you start multiplying this by the number of make-ups you need and it gets huge.