T-600 is neither your average puppet nor your average backpack, but this quick little clip from Stan Winston Schools shows that he's pretty impressive for both. Who said puppets had to be cute? [Stan Winston School]
There are two movies that I can think of (I'm sure there are more) that when you watch them today, they almost completely hide their age. T2: Judgement Day and Jurassic Park. I can't help but think that creative special effects like this are reasons why these movies still hold up.