Unfortunatley they are dificult and expensive to make.
I've decided to use ball and socket joints at the necks of my characters because I feel they give good smooth movments that can't be created using wire. As most attention is paid to the characters faces I need the heads to have controlled subtle movments.
Above are a selection of ball and socket joints that I have manufactured. On the left is a larger joint made from brass. This one is for the Theatre Usher. The other three are made from brass and steel and are for the two Mail Men and the Actress.
For the chunkier joint I used solid brass beads soldered onto brass rod. The sandwich plated are drilled brass bar, threaded on one side for the bolt to tie into.
These smaller joints are made from 5mm steel ball bearings that I drilled and soldered steel rod into. Its important not to scratch the ball bearings otherwise they will not give a smooth motion. The side plates are again made using drilled brass bar. The plates are held together using M2 nuts and bolts.
On either end of the joints I soldered K&S to alow them to slot onto the shoulders and the head. To see the joints on the puppet armatures check my previous post.