My recommencation would be to find a good 3D modeller who is interested in doing requests.
Give him a Halo 2 model and tell him to recreate the individual green armor parts, creating each of the designs in the armor.
Then when you "print" the 3D models, they'll come out detailed, in seperate parts which you can attach to a black suit of some sort, since most of the details on the Halo 2 models are actually just very nice texture work.