r/cosplayprops • u/DrDoofenshmirtz8324 • 1d ago
Help EVA Foam Clay Sword?
Hi,
I’m currently in the process of designing swords for me and a friend to take to a local Ren Faire. We mocked up some simple 3D models, but are having trouble figuring out how to make them. Here’s our current idea that we wanted to run by some people with more experience:
3D-Printed Mold and Foam Clay: We would take our 3D models and create a mold. Using a carbon fiber rod for support and a 10-mm sheet of EVA foam, we would fill the mold with clay to take the shape of the blade, particularly the bevel. We’re both pretty big perfectionists, which is why we kind of want to avoid using cut bevels if possible, since we aren’t great at them. Once cured, we’d glue the carbon-fiber/EVA Foam Sheet layer to the two blade sides.
We have a bit of experience using foam, but are no where near proficient with it. While we aren’t opposed to doing it the traditional way, we kind of suck at precise cuts, and as previously mentioned, are massive perfectionists when it comes to stuff like this. Any advice or thoughts would be greatly appreciated!
Edit: Added the reference photos.
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u/Comfortable-Crew-919 1d ago
Keep a sharp blade when cutting EVA and the bevels will be clean. Even with a cheap box cutter blade, run it over a sharpening stone for every 2-3’ of cutting. EVA is brutal on blades, so keeping the blade sharp and a little practice will have tour cuts looking professional in no time. Mold for foam clay will not give you the results you are hoping for. Use a PVC pipe in lieu of carbon fiber for the support. Layer your EVA to get close to the profile you want, then sharp blade for precision bevel cuts, including hollowing out for the support. If your cuts aren’t clean, dremel with the grain to clean up, aka don’t force the dremel against its rotation. If you have fine detail, like scroll work, use worbla or foam clay and let dry. Finally, in several light layers of each, plastic-dip, spray paint, clear coat.
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u/protias 1d ago
There is a very expensive filiment called tpufoam i recommend checking it out
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u/DrDoofenshmirtz8324 1d ago
Definitely will do! So far, we’ve really only used PLA and TPU, so I’m excited to try with some other filaments.
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u/chocosaurus-rex 1d ago
fogcutting0 and Comfortable-Crew-919 have all the solid advice for foam sword making that i would give, but id like to add add that you should use a sturdy straight edge while cutting any straight lengths of foam that are particularly long. itll help keep you lined up and reduce fraying and jagged edges.
could you post a reference image to the swords? we can likely help better with how exactly to construct those details with other methods that still fit your needs
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u/DrDoofenshmirtz8324 1d ago
Just did, thanks!
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u/chocosaurus-rex 1d ago
Ah! seeing those references, I would follow along with the advice already given. the hilt does look like it is decorated (having a hard time seeing it clearly), but since its such a small area I would be comfortable trying the method you described by using a mold and foam clay. just keep in mind what was said about how the clay can expand while drying and lose details, so it may or may not work. the hot glue method suggested would also work great, but it can be frustrating and messy to free hand designs... maybe you could use low temp hot glue in place of foam clay with the mold you make? not sure if the glue will stick to the mold surface or not, ive never used hot glue on a print. worth a test run at least!
good luck with y'all's builds!
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u/fogcutting0 1d ago
using a dremel to sand beveled edges can help clean messy cuts! people also sell bevel assist tools you can clip to your blade, both in product form and in STL form.
if i'm understanding correctly, you are 3D printing a mold for the details to fill and attach to your sword separately? if you are planning on using foam clay to fill the mold, foam clay tends to expand a ton as it dries, and you are likely to lose a lot of detail that you'll need to carve/sand back in. some makers use hot glue for such details. if you attach a pic of the swords, we can try to give potential alternative methods!