answer:I’m not a fan of Trigun or any anime, really, but I’ve been to a few cons here in Toronto. Most of the time when people cosplay as characters with gigantic weapons or the like, they’re made of cardboard. You’ll have to carry it around with you all day – you’re going to want something light. A quick Google of Nicholas Wolfwood cosplay shows that some people in the past seem to have used styrofoam for the cross – that might be an idea as well. So far as clothing and accessories go, thrift shops are your best friend. You never know what you’ll find that can be repurposed. There’s a page here that shows a crazy awesome Wolfwood costume. Maybe that site will give you some ideas?