Aluminum is a great material. It's basically like a really, REALLY hard wood. You can work it with basic hand tools, and basic power tools, into custom shapes that are very strong. Then you can "tap" it, which means "put screw threads into it", so that you can connect puppet parts. Now, if a puppet part breaks, you can replace just that ONE broken part.
For anyone serious about making their own armatures, aluminum is a good material to focus on. You can get very good, durable, effective armatures (the block kind), but you don't need massive equipment or super specialized training.
These are bits for our current stop motion project. They came out pretty sweet.
We'll be posting in more detail about the project as time goes on, so be sure to check back.