I began doing a paper mache cast of a liner from a bike helmet. I used wood glue thinned with water as a paste. All told there were about 4 or 5 thin layers of glue/water.
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After I had a dome shape for the helmet I used cardstock to rough out the shape and other details.
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Once I had the basic shape in place done with cardstock, I used that as a template and cut the forms out of cardboard. I used cardstock initially because it was simply easier to work with.
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I noticed that the helmet was beginning to look out of proportion and cut about ½ inch out of the face. I used shims to reconnect the whole thing. This left a few gaps in the face, but I was able to shore those up with cardstock. I’m not worried about the remaining gaps because I can fill those in later. Also, I cut a lot out of the back.
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I added a few more details from the model like the tusks and the ear boxes. I went a slightly different direction with the tusks than the model shows. First, it was difficult to get a conical shape that seemed to fit with the proportions. Secondly, I didn’t really like the way it looked. Instead, I went for a little more rectangle approach. I’m still not sure I like the tusks, but it does provide me with a place to put LED’s at a later date. The helmet also looks a little bare without them.
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I wasn’t happy with the overall look of the helmet. The dome was starting to look too egg-shaped and it just looked massive. To fix part of that, I cut the dome away from the inner ring and pulled it down. This helped with the egg-shape and made it smaller from top to bottom. Because the shape had changed though, it created some gaps where the inner ring met the dome.
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I went ahead and added a few more details. I wasn’t sure I would add the “teeth” because I didn’t love the way they looked. However, after doing a mock up, I didn’t hate it so I figured what the heck. Once assembled, I used wood glue thinned with a little water to coat the entire helmet. I painted on 5 or 6 thin coats of glue/water. This helps to stiffen the whole thing. It also helps to fill in the cells of the cardboard making the whole thing much more rigid.
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Stepping back from it I noticed something … it’s fricken huge!!!. It’s much bigger than any other helmet I’ve built this way. I simply can’t tell if its out of proportion or this is just the way it looks. To my way of thinking, the goggles are the focus of the helmet and everything else has to be in proportion to them. The goggles fit pretty tightly to the dome and couldn’t be made much smaller. As I sit and look at it, everything appears to be in proportion. However, side to side, it’s about 11 inches. In comparison, the black helmet is about 8 inches at its widest. Front to back, it’s about 12 inches while the black helmet is about 10 inches. I can’t tell if this is a flaw or simply the fact that it’s a different style of helmet. On the plus side, there is plenty of room inside for padding, lights, batteries etc.
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I don’t actually use bondo to fill gaps and smooth out the surface though. Instead, I use drywall mud aka joint compound. Joint compound produces a ton of dust when sanded, but its non-toxic. I don’t recommend inhaling the stuff, but at least you can use a breath mask rather than a ventilator. Another plus is that is relatively cheap. I bought a 1 gallon bucket for about $7.00.
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To finish it I use sand paper to take down the big stuff then move to a damp sponge to do some wet sanding. This allows me to fine tune some areas and fill in some holes. A light sanding after that to smooth it all out.