I found some PEP files here ( Half-Life 2 Papercraft: HEV Suit Chest Armor )
Personally i think there are better and more complete archives somewhere though... -_-
Re: Help Converting a NERF Recon into a Halo Reach MA37 AR and an SRS 99 AM Sniper Ri
As much as i hate it, there are always pepakura files on: Halocostuming.wiki.com