As some of you may be aware, I was building my Iron Man Costume out of Aqua Resin - A widely used US water based casting and laminating product.
Well, the long and short of it is that I've found a very good UK alternative which has been around since 1984, but seems to have been one of those best kept secrets for some reason. It's called Jesmonite. Side by side, it seems to handle exactly the same as Aqua Resin, it's non-toxic and non-flammable, and also pretty cheap.
I've built the back of my Iron Man torso from Jesmonite and I'll be continuing with the legs like this too.
I've also done some strength and destruction testing on Jesmonite including a YouTube video which is embedded in this page:
There are a few UK suppliers for the product (including me), but take your pick and let me know what you think. I've used it with standard fibreglass surface tissue and mat, and I think it's as strong as rocks ;-)
Here's the Iron Man piece made from Jesmonite: