If you are going to print the Size A, you need to understand which extended design parts are available to print...

The size A evolved as I worked the design, there are additional parts available that are either exclusive to the size A or have otherwise been combined into the base model for the size B and C

Chin Front with M4 bolt modifications - Those M4 Hex heads really up the game.

http://www.thingiverse.com/thing:163439

Perforated Visor for Halo Helmet - want to be able to see through a printed visor?

http://www.thingiverse.com/thing:165110

Halo 4 Helmet Size A Big Pieces - Combined components where separation was unnecessary if you have a replicator 2 size build volume.

http://www.thingiverse.com/thing:168678

Halo 4 Helmet Full Size A with tiewraps - take control of that wiring harness, with built in tie wrap "warts" in the inside of the model.

http://www.thingiverse.com/thing:169295

Halo 4 Helmet Full Size A Peak with Batteries - you need somewhere to put those 9 volt batteries, and these built in clips rock.

http://www.thingiverse.com/thing:171912

Want a PETG vac formed clear visor ready for painting in your favorite metallic?

http://www.thingiverse.com/thing:217267