I will be curious to know what this weighs when you finish, to help me decide whether to go with fiberglass or foam when I get around to building my hunter (I had the same idea about a year ago to do a hunter for accompanying my kid's Master Chief outfit). But even if I do fiberglass, I think the spines should still be foam to avoid impaling anybody. I was also considering some sort of pulley system for raising and lowering them to help with getting through doorways and just being a neat effect. One of the nice things about somebody else doing this first is I get to learn from your build. SLC is probably where we'll end up going too now that Tree City Comic Con has been discontinued in Boise.