I have seen people having a lot of problems trying to print the blueprints the correct size. Here is a very simple method I used:
Resize the blueprints so that when you hold a ruler up to the computer screen it exactly matches the scale.
Use clear plastic (overhead projector plastic) to trace the patterns right off the screen. The pieces won't fit on most mortals' screens, so trace what you can, then scroll and trace the rest.
This method took me a few minutes to create patterns for all the armor pieces.