Hey everyone, new here, and to Papercraft in general. It's pretty fun!
I've made the Guy-Man V2 helmet, and would just like to give some advice and info I've gleaned from my sizing trial-and-error.
First, I'll say that if you're planning to make this helmet, you definitely need to scale it down, unless you're 7-8 feet tall. I had to scale it down from 27.5cm to 22cm (that's 20%!) The Guy-Man helmet is supposed to fit pretty closely around the head, and by the time I bondo and vacu-form it, it will be plenty big (it already fits over my head just fine). And just for reference, I'm 6'3" tall, and my head is 22in around (or about 56cm), so I'm of larger than average build and still needed to scale down a lot.
Also important is the fact that the pattern is flipped around when you open the file, so be sure to hit the "flip development" button and rearrange the pieces before you print. I got mine down to 8 pages (from 20 pages!).
Here's a picture showing the 27.5cm helmet vs the 22cm build
And here's one of me wearing the helmet (sans the ear pieces).
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I hope this helps some people save time by giving a better idea of scale to eliminate some trial-and-error
~Bane