I designed the armatures based on a few sources which are from Susannah Shaw's book Stop Motion: Craft Skills for Model Animation and Anthony Scott's www.stopmotionanimation.com which I think is the best place to learn about everything stop motion related. They have a great handbook for beginners and if you cant find what you need in there then ask a question on the forum and your guaranteed a pretty damn good answer. Also there are a lot of professionals and generally very talented people on there. An endless resource.
I have made the armatures with 2mm Aluminium wire, rubber cork, aluminium tubing and white putty.
They are very sturdy and have confidence that they will last the duration of filming.