I'm not sure if I have mentioned this EBay Store before but it has a extensive supply of specialty sculpting items. They have some tutorials as well. If anything a great place to start a wish list

http://stores.ebay.com/The-Morezmore-Estate

Billy D.

I followed the link to their blog and fond a post on ball joints.  While this is built in fimo and is a "doll" the concepts here could be used for a marionette or even rod puppets.  I was especially interested in the section on sculpting the hands since I always struggle with that. I am actually linking to part two of the article but you can back up two part one if you want.

http://morezmore.com/myblog/2010/01/16/bjd-2/