You could
1) Download a free trial 3D modelling program like
Sketchup.
2) Track down some 3D files of the Mark I like
these.
(although that particular one looks little flat to me).
3) Download
Pepakura. Its a paper folding application.
4) Import the Mark I 3D file into pepakura, unfold it into many, many,
sheets.
5) Print the sheets onto 110lb. cardstock and carefully cut, score folds,
fold, and glue together the armor.
6) Fiberglass resin the armor for stability.
7) Use full fiberglass on the inside for strength.
8) Bondo the outside to get it smooth.
9) Paint it and come up with a mounting system to wear it.
10) Enjoy!
Note: All credit for this method goes to the 405th.com. I read their
many informative tutorials
here.