Non-wearable Helmet Fill Material (For Pepakura)

[aurias]

So I'm working on an actual "lifesize" Chief for my game room. I'm doing the helmet first. I have completed (except for final details and painting) a wearable chief helmet, but this one won't be wearable obviously using the same pepakura file.

Because it wont be wearable, I want to fill it with some material to provide rigidity, but not make it unreasonably heavy. I've considered many different materials, but I haven't really found a "perfect" solution.

I've considered building sealing foam, or expanding foam, not sure of the technical name. But I'm afraid the adhesive properties as it dries will work very well inside the helmet and basically explode it.

I've also considered lightweight hydrocal, but I'm not sure how lightweight it actually is as I've never used it. Or if it's adhesive properties will be good enough once it dries.

I can also brace the inside of the helmet with cut-to-length pieces of wood or other material if needed, then fiberglass them in.

Anyway the reason behind it is that it will be much easier to add detail if the helmet is filled with something I can actually work into. It will also allow to easily mount this thing on a rod for placement on the body.

Any ideas would be appreciated!

 

[Katsu]

That's an interesting idea. There are two things to keep in mind on this...
First, you're going to want to do one layer of rondo or two of fiberglass inside the helmet. This will back it up so you can smooth the outside, unless you want it looking boxy and chintzy, which is fine! But if you want to smooth out the outside, you'll need at least the layer of rondo/fiberglass inside. But this also serves a double purpose of protecting the paper from being pushed out by whatever filler you use.

My personal opinion is to use fiberglass, since it's a lot thinner and lighter than rondo, and airbubbles aren't a big concern if you're not wearing it. Once that's been done, get a few cans of this stuff:

I used it to fill my needler, and it's pretty neat stuff, careful though because it's water catalyzing, so don't wash it down the drain or you'll clog it up. It's lightweight without compromising a lot of strength.

That fiberglass between the paper and the foam is important though, to maintain the shape of the piece.

 

[aurias]

That's an interesting idea. There are two things to keep in mind on this...
First, you're going to want to do one layer of rondo or two of fiberglass inside the helmet. This will back it up so you can smooth the outside, unless you want it looking boxy and chintzy, which is fine! But if you want to smooth out the outside, you'll need at least the layer of rondo/fiberglass inside. But this also serves a double purpose of protecting the paper from being pushed out by whatever filler you use.

My personal opinion is to use fiberglass, since it's a lot thinner and lighter than rondo, and airbubbles aren't a big concern if you're not wearing it. Once that's been done, get a few cans of this stuff:

I used it to fill my needler, and it's pretty neat stuff, careful though because it's water catalyzing, so don't wash it down the drain or you'll clog it up. It's lightweight without compromising a lot of strength.

That fiberglass between the paper and the foam is important though, to maintain the shape of the piece.

Thanks! I was planning on doing at least a couple of layers of fiberglass inside anyway, just as you said, to allow fine detailing (a good background material I suppose). I'm glad to hear it also gives enough strength to maintain shape with that type of filler.

What you posted looks similar to that seam/joint filling expanding foam, so I believe it would definitely give enough rigidity to the helmet while keeping the weight down. It will also allow a nice opportunity for mounting it with a rod.

Thanks again

 

[misfitjh]

What if you used a foam head like the ones they use for wigs, then add spray foam to take up the space around it. With the helm fiberglassed there will be no probs using spray foam on the inside.

 

[aurias]

That could work also, reduce the volume at least of what needs to be filled.