I'm really not into costuming. I'm a hard-core reenactor! Mostly Vietnam, but some WWII also. I have a fleet of 10 military vehicles, enough weapons for a platoon, a house full of uniforms, and so many tents that I can house about 100 troops.
But the Colonial Marines are so bad-ass that I put a Sci-Fi Military 'costume' in with my uniforms. 'Aliens' is simply the best movie ever made.

Also, in our reenacting group, some of us split off into smaller groups and do Mobsters (not me) or foreign Military forces like British SAS.

As a group, we even do some more exotic OPFOR like Soviet Airborne VDV. With these awesome impressions, we usually roll out to airsoft events, and use the experience for PR and for training.

And then, just recently I did another sort-of-costume, but it's still Military. All I had to do was get a couple different items, like a repro M1911 shoulder holster to mod up, and a new-production Aussie slouch hat, and make some custom painted camo print pants and BAM! I'm Jungle Recon! HELL YEAH!

Officially, he's the 1984 GI JOE "Recondo" Jungle Trooper. But due to a new YouTube Channel called "Action Figure Therapy" this charactor is probably better known as "Jungle Recon".
Here's my favourite videos:I Love My Job
http://www.youtube.com/watch?v=VIylwth99WgHow Does A Mustache Help In Combat?
http://www.youtube.com/watch?v=PiWkhET56uAReflective Belt PSA
http://www.youtube.com/watch?v=44UtJhQKP78