Using the brown paper bag rough mockup, I went ahead and tried to make sure all the lengths were actually right, then redrafted the pieces by hand, scanned them in...realized I didn't have Illustrator on my computer and downloaded Inkscape. Yay, Inkscape! So far, I am loving it and it's an open source program! So, that's a small plug for Inkscape.
http://www.inkscape.org/ Anyway, scanned the paper bag drafts, traced them, made vector graphics out of them, and began working on the design. They are not fully adorned yet, but I think they're at a stage I can print them out, cut them out, and do a mockup to be SURE I have the size and proportions right (they won't be on this picture because this is just an image of them all together as best I could fit them on a page).
Anyway, moving along. If I can get this right, I think a lot of the rest of the armor will be easier--I already know how to do bracers and stuff with Sintra. The hand-pieces might be a little challenging. But I figured that the headpiece will be one of the most distinctive pieces so if I can get that right out of the gate, I'm well on my way and will feel more confident as I move along.
So... that's my progress for this weekend. (Pardon the crappy resolution--it is a gif file so to see it better you have to click on the image below so you can go to the full-size version.)