From Halo Costuming Wiki

[edit] Entry-Level Costumes

Entry Level Costumes are costumes which are relatively cheap and easy to make.

[edit] Soft and Vacuform

Marines' armor ranges from nothing- as seen in the Flood levels of Halo C.E.- to the fixed, simple plates of early Halo C.E., to the jointed armor of the Halo 3 marines. Overall, though, it's re-create-able largely with fitted BDUs and vacuformed armor.

There are a few different Marines from the different areas of the different games:

• fixed-armor Halo CE marines.
• unarmored. boonie hats, rolled-up sleeves, different camo?
• Halo 2 style
• Halo 3 style- hinged armor

[edit] Soft, Vacuformed, and Molded Helms

ODSTs have more armor than Marines.. but then again, it's not nearly as detailed as Spartan Mjolnir armor. It's probably vacuform-able.. and ABS plastic is already black. They also require a more complicated helmet than the Marines' open-faced deal, and they supposedly have a sealed suit, which means their BDUs need to be fitted closely and carefully to them, no skin can show.

There are two basic ODST variants:

• Halo 2
• Halo 3