My Favorite Cosplay Mold Making Materials

Cosplay Mold Making Beginnings

When I began cosplaying in 2014, cosplay mold making seemed like a mysterious, daunting kind of maker-magic reserved for the cosplay elite.  Oil based clay that never dries? Resin that starts “kicking?” Tin- vs platinum-cure silicone? It was all so overwhelming.

And yet, the prop that inspired me to dive head-first the cosplay world was none other than this cast helmet by Volpin Props. At the time, all the materials and techniques described in his article felt so far of my reach. I instead began my cosplay journey with products like Worbla, expanding foam, and EVA foam. But there was always a voice in the back of my head urging me to try cosplay mold making. It was my ultimate goal to be able to sculpt and cast durable props and replicas.

Fast-forward and I now own and operate my own business selling handmade resin artwork and commissioned props and cosplay. I wouldn’t have gotten here without some key maker tutorials, a little patience, and my favorite cosplay mold making supplies. In honor of my upcoming ten-year anniversary as a cosplayer, I thought I would share some of my favorite cosplay mold making materials and tutorials with you. This will just be an overview of a few of my favorite materials and techniques, paired with the tutorials that helped to learn how to use them.

I will preface this by saying my experience is currently only with Reynolds Advanced Materials (Smooth-On) products. I have a local Reynold store in Orlando, and so I am easily able to visit, pick the brains of their staff, take classes, and purchase sample materials. While these are not the only cosplay mold making materials on the market, they are what I will be focusing on today.

Also well worth mentioning, if you are starting to dabble in mold making and resin casting, please be sure to follow all safety guidelines provided with the materials you choose to use. A respirator is an absolute MUST when working with these chemicals.

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Flexibility & Cost Savings with Brush-On Molds

My first mold was a small brush on using Rebound 25 which I used to cast clear hollow “gems” in SmoothCast 325 for my Diablo 3 Crusader pauldrons. At the suggestion of a Reynolds’ employee (Thank you, Amee!) I purchased a sample kit of Rebound 25 brush on silicone, a small bottle of Thivex, and some gypsum strips. Then, it was off to the races! You can see how this first mold took shape in my “Pauldron Perfect” post.

I am a huge fan of hand sculpting wearable art — masks, helmets, horns and the like. So Rebound 25 is my go-to when making molds for masks and helmets. It allows me to save cost by using a minimal amount of silicone over complicated and bulky shapes, and it is platinum-cure, meaning it has a great durability, flexibility, and a relatively long shelf-life. Keep in mind this kind of mold will require some kind of hard shell in order to keep the silicone’s shape when casting. I use either PlastiPaste II, or some simple gypsum strips, depending on the size and complexity of the mold.

I also used Rebound to mold the Dragon Skull helmet I finished earlier this year. Even at 20” x 15” x 9” I only had to use 1/3 of a gallon of Rebound for the entirety of the mold. Given the size shape of the helmet, I opted to use PlastiPaste II for my four-part mold shell. Each section screws together to hold the silicone safely in place while slush casting. The helmet itself is cast using SmoothCast 300 dyed with a bit of So Strong brown to tone down the ultra-bright white of the 300. I find SmoothCast 300 to be an excellent choice for slush casting specifically, since the pot life (time the mixed urethane remains “liquid”) is 3 minutes.

Copies of this helmet are currently available for sale in my shop.

Large Prop Molds & Degassing Silicone

I first began making molds regularly during 2019 with the creation of my Greatsword of Artorias. The first of several molds was an open top, one part block mold used to cast a sculpted “wolf” face plate for the sword hilt. Since I needed two identical pieces for either face of the hilt, I opted to mold and cast this piece. I also created a one part block mold for the cross guard for the same reason. For both of these molds I used MoldMax 30, as it was relatively affordable, and seemed a good shore hardness for my needs. The downside is MoldMax 30 needs to be “degassed” in a vacuum chamber to remove tiny air bubbles that become trapped in the silicone when mixing. With smaller molds degassing isn’t a big issue, so long as you have a vacuum chamber and vacuum pump. Just be sure to use a large enough container so your silicone dosn’t spill over the lip of your mixing cup in the process!

Punished Props gives a quick look at that degassing process in their one-part mold making tutorial here.

The “No Vacuum” Mold Making

When it came time to create block molds for the Greatsword of Artorias, I knew it wouldn’t be feasible to degas such a large amount of silicone. The two- and three- part block molds I created for the Greatsword of Artorias were going to be BIG—as to be expected for a nearly six foot long sword. Both the hilt and blade were molded using a nearly three gallons of MoldMax 29NV. MoldMax 29 NV is a low viscosity silicone, meaning you can mix and pour large batches without worrying about trapped air bubbles post-mixing. No need to “degas” the silicone, hence the “NV,” for “No Vacuum.” A blessing when you’re mixing and pouring large amount of silicone for cosplay mold making.

The Greatsword of Artoias was such a large piece to tackle on my first time mold making for cosplay. I am skimming a lot of details in the process here, but I will say it was definitely a labor of love with lots of ups and downs along the way. I wouldn’t change my decision to learn the process the way I did, though. You could say I learn best the SmoothOn way—by getting out there to “Make It Now!“

Hollow Castings with EpoxAcoat

Both the blade and hilt of the Greatsword were cast using EpoxAcoat Grey, backed with pieces of woven fiberglass cloth. EpoxAcoat is a thick, brushable epoxy coating that sticks to the mold walls to create a hollow casting. Great for huge casts like oversized anime swords or bows. For additional support I backed the hilt with Feather Lite resin. This kept the piece relatively lightweight but still gave it more inner strength to support the addition of the blade casting. I later adjusted to filling subsequent hilt casts with SmoothCast 305, mostly because it has a longer pot life and pour time for such a large piece.

I also used EpoxAcoat for my Black Knight Halberd and Mythical Raider Axe. Replicas of the Greatsword of Artorias are also available for sale in my shop. I have sold a handful over the years, and will likely be retiring the mold sometime in 2024.

Super Black Resin and “Cold Casting”

One of my favorite products that I use on nearly a weekly basis is SmoothCast Onyx Fast. Specifically, I use Onyx in conjunction with a wide variety of SmoothOn’s Cast Magic metal powders. Sometimes this method of casting resin with metallic pigments is called “cold casting” since it results in a metal-looking cast, without the use of actual molten metals. In my opinion, SmoothCast Onyx is the absolute best resin to cast with to achieve a shiny, metal-look finish in your castings. Similar to SmoothCast 300, Onyx Fast also has a short pot life, meaning it is easy to use in “slush” castings, which is how I most often use this material.

One great example of this is my Mask of Dagoth Ur. I sculpted the original by hand using Monster Clay medium, then molded using Rebound 25 and creating a two-part plaster shell (no surprise here!). Before slush-casting in Onyx, I brush in a good layer of Goldfinger metal powder. Having that metallic gold look straight out of the mold means right out of the mold my mask is already 50% finished. And I can be more confident in the final piece my customers receive knowing that metallic finish is baked into the resin itself.

I currently offer made-to-order Dagoth Ur replicas in my shop, as well as other styles of resin masks and helmets.

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Conclusion to Cosplay Mold Making

With the experience I’ve gained over years of practice, I can confidently say mold making is well worth bringing to your cosplay crafting arsenal. It’s okay to start small, but never be afraid to push your boundaries try new, bigger things as you go. The materials and techniques I cover here are merely a sliver of what is possible in the cosplay mold making world.

As I mentioned at the start of this article, I have now been operating my own business selling handmade resin artwork and commissioned props and cosplay since 2019. This past week I had the honor of being featured by Reynolds for their Customer Spotlight. It is strange and humbling to feel like I’ve come full circle—from novice to Master—these past ten years. I hope it serves as inspiration to everyone who is interested in tackling cosplay mold making for the first time!

If you would like to see more of my work, check out my Cosplay Portfolio, or consider supporting me with a purchase from my Web Shop. I also regularly post current works in progress on Instagram, as well as shop updates and plenty of convention shenanigans. I’ll also include a list of all the materials mentioned in this article below for you to come back and easily reference.

Erei mu grind!

**Full Disclosure: I get credit when you purchase items via my Amazon links in this article! Any profits I receive from Amazon will go directly back into more blog posts and tutorials. Thanks in advance for considering a purchase 🐲