In case you are just starting your costume, (like me) I wanted to show you that you can still get started with a cool cardboard costume and finish before Halloween (you will have to hustle). Although I'm going as a grasshopper, most elements are the same, I'll just be dealing with extra legs and antennae...
Just start with long cardboard strips, (mine are a rulers width), and drape them over the shoulders attaching horizontal strips as needed.
You can build a structure pretty quickly on which to start gluing cardboard skirt pieces and armor layers.
The rounded layers on the shoulders above are made by tracing a variety of bowls and plates, cutting them in half, then folding them and gluing them into place.
Really, it's not about the cardboard though, is it? It's about trying something new that you have never done before....it can make you sheepish. Well, I'm here to say: You can do this!
My inspiration: these incredible costumes from last year's challenge:
Archery Knight by Rachel and Tom Morgan
Cardboard Knight Costume by wrnking via Flickr