Heres the link to how to make one...
http://www.wallaceandgromit.com/forum/read/8594/5
I can't find the general info post, so I'll just post it here...
An armature is the inner frame of a stop motion puppet. Like you and me, we have a jointed skeleton inside us that supports our body mass. The skeleton helps us move and not slip around like a blob of jelly. (See Picture)
Because a skeleton enables us to support ourselves, stand up, move limbs without them bending unnaturally, we need a skeleton or armature our puppet.
A stop motion puppet's armature all depends on your film, character, budget and skill.
A simple wire armature requires only annealed aluminium armature wire for the spine, arms, legs and neck, epoxy putty or similar, a drill and some pliers.
The next step up would be a B&S armature. Ball and socket armatures can be hard to make by your self, if you don't have the right equipment. Ball and socket armatures are more similar to a human skeleton with socket joints in the shoulders, elbows, knees, ankles etc. You can get a much smoother fluid movement with B&S armatures.
If you lack the equipment and time to make your own, there are many ready made armatures out there to buy. There are links at the end of this post, where you can buy them. These armatures are also more robust and easy to use, with no problems like breaking wires or wire un-twisting.
Sorry, its a bit long.