if your going to manufacture joints to sell then im going to be no good to you however if you are a film maker i may be able to save you a shitload of time and money

i used to do a bit of stop motion.... i used to split diffrent size chain and use two of the figure of eights to pinch the balls, countersunk on one side so they dont eat your ball

id buy the brass balls from a fishing tackle outlet and solder them onto the end of the brass rods i was using for bones

sooooo... imagine you have two of the figure of eights from the chain on either side of two of your balls then you wind fishing line into the waist untill you have the type of tension that you are looking for

with a small chain i have made fully articulated five finger hands full set of joints that measure aprox 10mm across the palm, ill stick a picture up next time im home if you are interested (they are well posh)

a small cnc would be invaluable if you are making screw driven articulated heads etc :)

have you any work up on vimeo or youtube ?????