I hear about how that is how aftermarket head forms are made, but does anyone know the actual process?
Sorry Tom, I am not sure what you mean here. To the best of my knowledge the heads are sculpted not carved… or do you mean sculpting a core upon which you add and sculpt modelling clay for the features?
This might be of interest to you:
More and more are now being created by CAD, and the masters being 3D printed; especially the large scale personality likenesses.
The CAD ones I’ve seen were disappointing compared to the carved resin ones. That’s why I figured CAD is not the way to go if you want quality.