Foam vs Pepakura Unfolds - A Guide to the Difference

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405th Regiment Officer
Member DIN
I’ve seen a few times ‘round the forums where people have asked what the difference between a foam unfold and a pepakura (AKA pep, paper craft) unfold is. There’s a few key differences between them, so I’ve decided to write a short guide to help shine some light on the subject. In this guide I refer to “pepakura’ as the method, not as the program (I use Armorsmith).



Top: Low Definition foam unfold. Bottom: Low Definition pepakura unfold.
Halo 3 Mjolnir MkVI LD unfolds: Halo 3 - MJOLNIR Mark VI - Standard LD

Foreword: I have never actually done a pep build before – as in, taken it from the paper craft stage through to hardening and finishing. I have however, a number of times unfolded and made paper patterns that were then transformed into foam or fabric patterns, so I do have experience in the pepakura realm. That being said, if anyone has any advice for this thread, be it additions or suggestions for change, do let me know.

Please note this isn’t an unfolding or assembly guide, it’s just to explain the differences in files in the Armory, and anywhere else on the internet you may find pep/foam files.

If you jump into the Armory (it kills me not putting a “u” in Armory) you’ll notice some files have standard and “foam” variants within a file pack. The difference between foam and pep unfolds is the complexity. Here’s why:


List showing Halo 3 Marine unfolds with pepakura and foam variations.

1. Material properties. Try taking a sheet of paper and bending it over a spherical object. You’ll notice how if you want to try and wrap the paper around, it’ll crinkle and fold on itself. Regular paper (and cardstock too) doesn’t have any stretching properties. On the other hand, if you did the same with foam, you can get a lot further before it starts to fold – because it can stretch and compress. This anecdote is to say that whilst foam can stretch in multiple dimensions at once, paper can’t. So you’ll find pep unfolds have a lot more pieces to print, cut and stick together over foam unfolds, to compensate for the paper’s material properties to make curves. With foam, it’s much easier to heat the piece and bend it into the shape you need.


A ladel, the best thing I had to help demonstrate.

Attempting to fold paper over the ladel

Attempting to fold foam (8mm) over the ladel.

2. For a pep file to get all the intricate details for a piece, those details have to be cut, folded and glued together to make them. On the other hand, typically for foam parts, these details can be done with a multitude of techniques, such as scoring and heating the foam (or using a wood burner/soldiering iron), stacking pieces, sculpting layered foam, foam clay, etc. To simplify foam unfolds, these details are often removed or segregated as it’s easier to add them in once the bulk of the foam piece is done.

3. The final big difference between the two is due to the difference in thickness in materials. Paper is obviously extremely thin, whereas foam commonly ranges from 1mm-12mm, and even higher. Remember that two faces come together to form an edge. Where sections of armour or props have an edge, paper patterns need to include both faces in the unfold that make up the edge. For foam though, the thickness of the foam acts as a second face, so templates only include the larger face – up to a limit, where another piece of foam may be needed to make bigger faces. This is a little hard to communicate with words, so hopefully this image helps:



Notice how one sheet of foam has thickness that creates a face, but the paper needs to be folded/glued together to create a second face

4. Pepakura unfolds will generally contain some extra features that foam ones don’t. One such is the addition of tabs onto the edges of individual pieces. These tabs are what connect pieces to each other with an adhesive. Some pep unfolds will also have additional supports to hold pieces in shape while constructing and strengthening the build. This screenshot of the LD (Low definition) pepakura model for the Halo 3 Mjolnir MkVI helmet shows both features:


MkVI pepakura unfold showing support for the brim, as well as the tabs on individual pieces.

Hopefully that sheds some light into the differences in the unfolds in the Armory, and like I said above, if you guys think I missed something, or what I said contradicts your thoughts, do let me know! Remember, there is no “better” method of making armour – it all depends on what you are most comfortable with, and what tools/materials you have access to.
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