I'm seeing a lot of questions on this, so I figure I'll recap for anyone unfamiliar.
If you are familiar with photoshop, this is a fairly straightforward process. Looking forward to actually doing it.
Make sure you are viewing the rulers in photoshop. The actual photoshop rulers. (Click View -> Rulers).
After you take your measurements and calculate for the EVA foam thickness (in the codex), expand the BLACK measurement bars that are provided to the correct length using the photoshop rulers.
Then move your black rulers to the center of the image so the top arrow lines up with the top of your measurement bar. LOCK your measurement bars in place (in the layer sidebar) so they do not resize. Click any other layer in the image (so the armor is highlighted).
Then resize/transform the armor layers. they should all be linked, so they'll shift and resize together as one. once the top and bottom arrows are perfectly aligned with your measurement bar, hit enter (securing the vertical) and then transform again and align the horizontal arrows. Once this is done, your armor is now resized.
So now what? Now, go ahead and hide the measurement bars. You're done with sizing.
To get a clear print, you'll want to rasterize each layer. You can multi-click (ctrl+click) each layer in the side bar, then right-click and select rasterize layers.
Unlink each layer. Because as foam pep works, each layer is a piece of the foam you'll print and cut out. (Look at an individual layer and a complete suit of armor and you'll see it. The foam is stacked in different shapes to give the n7 armor its look - each of these layers is now sized and scaled to the size of your armor piece.
The file N7_platform (A4 or Letter sized, depending on what you use) is basically a blank canvas, sized for one sheet of printer paper. Drag each (or multiple) layers onto this ensuring they do not overlap.The more you can fit on a page, the less paper/ink you'll use.
Print it and use it as the template for your foam.
Hope this helps. Good luck, troops.