Dude, this isn't a site where you ask people to make you stuff.
You either do it yourself, or you make something else so you can trade the pieces for the AR.
Read the stickies, download pepakura designer v.3 (google pepakura designer and click on a like that leads to something like www.tamasoft. something) and head over to www.halocostuming.wikia.com to get you started.
Welcome to the 405th
I noticed
I say start with something easy, don't go making a gun. Start with something like the Halo 1 marine or Halo 2 ODST armor to get the hang of it then do harder and harder pieces to get skill
Have fun pepping bro.
Oh, and one more thing.
Most of the armor pieces are in this file: http://www.4shared.com/file/rRBX15Dy/_2__405th_Pep_Pack.html
It was HeavyGunner's idea, and it's awesome.