You might want to drop this in requests for Pepakura (
here). Also, though most of us will know exactly what you are talking about, reference images should always be added.
View attachment 30939
It looks very similar to the other reach armors, but at a smaller scale. I would take a look at some of the other Noble team armor and scale it down. Due to the size difference from the other arm, you might want to bump up the scale a little on the left arm and then make the right arm as compact as possible to preserve the scale. Take a look at Fullmetal Alchemist cosplays of Edward, as the trouble they tend to have is making a full covering of an arm look that same or smaller than a physical arm. They have some very nice "robot" arms and you can pull from their designs to help you.
Hope this helps.