I will be attending all three days in my Spartan IV suit along with my friend who will be an ODST. I am so pumped to finally meet some 405th members! Also the idea of a Halo themed wedding is genius.
Will we be doing any demonstrations at the table? The foam method would be an easy demonstration to do. Something to the effect of building a foam Chief helmet over the course of the three-day convention, so people with a 3-day pass can check in every few hours to see how the helmet is made. Members could each take a turn whenever they feel like it an work on the helmet. I would be more than happy to supply the foam and all materials if this seems like a decent idea.
Also, as far as I know the Gearbox Union will be attending this year and will most likely be doing another raffle, and they usually ask for donations from the other vendors and booths. I think it would be cool to have the helmet built at the con and then raffled off at the con. So it's a double win, people get to see how a piece of foam armor is made, and somebody gets to take home a Halo helmet.
That's just an idea though, thought I would throw it out there.