You won't find 3D printable files in armory, but you can check out free 3D model index for printable models.
You can take a look at this one
If you are going to print for Cosplay, please consider the Modified ODST I created here:https://www.thingiverse.com/thing:3782505 This is an armor set remixed from a Pepakura armor files uploaded on the 405th.com forum. The files I made printable are...
www.thingiverse.com