Slush Casting Helmets?

So I have been working on a Pepakura helmet lately, I still need to do resin and bondo. And I was wondering if it possible to slush cast with Polyurthane Rubber? They used that material to make armour for Forward onto Dawn and the Deliver Hope Trailer and I was wondering if it is possible to do so? If not, what is a cheap material to use? I found a website before but I was so confused on witch material I need. I would post a link but I forget the website :3 Also when people say add resin to make the slushed cast item stronger, do you just add it in the same time with Part A and B?

I can't help ya with that rubber part, but I DO know that when I did slush castings of previous armor pieces, I made a mixture called "rondo". It's a mixture of bondo and resin. You want to mix it so that you can pour it, but NOT TOO runny or you will end up with a very drippy mess. XD

As for your question about adding resin to part A and B, I don't think you need to add resin if you are already using something else for strength. The ONLY time I have heard about adding resin is for the method that I just mentioned.

I know people have also used smooth cast and I am pretty sure you do NOT need to add any extra resin to it. Mixing different chemicals like that might not be a good idea, but I am not completely familiar with smooth cast and don't know how it would react if resin was mixed in. From what I understand, smooth cast alone is pretty strong though.

Hope that helps ya some.

Polyurethane rubber -is- compatible with slush-casting as far as I'm aware. However, you're going to need to ensure that you

A) get a reasonably good shore (toughness) grade for your piece (Shore 70A is at the same grade as a car tyre)
B) get a decently-thick wall on your piece (thin rubber will split easily)

Polyurethane rubber is -not- compatible with fibreglass/resin/bondo, so you're not going to be able to reinforce your pieces with it. Also, painting it might be a pain unless you can find a decent costume-grade latex paint to use. However, there's no reason why rubber armour pieces can't be done as long as you put the research and effort into them.

I would use Smooth cast but It's way to pricey. I failed to mention I need to cast multiple copies of helmet. So how good does Rondo work? Is it sturdy or does it break easy? Also whats the ratio when mixing?

I would NOT use rondo to make casts out of. Rondo is only something you want to use in order to harden pieces instead of using fiberglass on the inside. As far as the ratio goes, it's normally a 1:1 ratio and you want to use the catalyst for BOTH the resin and the bondo.

If you are looking for something to make casts out of, I can't be too much of help for that since I never dealt with doing cast molds since I prefer to work with foam because it's less toxic and safer when you have a baby.