"Pepakura" is a technique for making printable versions of 3D computer models. The printout comes with numbered tabs and edges that are matched up and glued together. When all tabs and edges have been joined, the result is a paper version of the computer model.
Pepakura models can be found on Star Wars fan sites. For this project, I used the files found here:
The software for working with these models, Pepakura Designer, can be found here:
A complete list of tools and materials is attached.
Step 1: Measure the child and determine the scale
Next, measure the arms from elbow to wrist for the gauntlets. It's important to size the helmet and gauntlets appropriately. The head must fit inside the helmet and the arms must go through the gauntlets. If these parts are not sized correctly, it will be very hard to use them in the final costume.
Measure and scale for all pieces. If you downloaded a complete set of armor models, the scale will probably be consistent, but this is not guaranteed to be so. The surface-worn parts like the shoulder caps, knee caps, and chest armor are more forgiving with respect to size, but should still be scaled to fit the child.