I’ve been wanting to upgrade my painting setup for a while now, and my switch last year from rattle-can to catalyzed primers and clear coats was the final push I needed to start planning. I also own a fantastic little compressor that, unfortunately, had developed an annoying leak. So I decided to tackle both projects at once! The whole project took me about a day (a few hours here and there, broken up by finding the correct fittings and parts), and less than $100.
Welcome to Part 2 of how I made the Winter Soldier Arm, a wearable piece for cosplay and photography I was commissioned to make that replicated, as accurately as possible, the cybernetic arm seen in Marvel Studios’ Captain America: The Winter Soldier!
In Part 1 I went over sculpting, molding, and casting. If you haven’t read that yet and are curious about those parts of the process, I suggest you give it a read first. And of course, if you’re more interested in grabbing a Winter Soldier Arm of your own than learning how I made mine, I’ve got you covered:
- If you want to finish your own kit: Winter Soldier Arm (Resin Kit)
- If you just want one delivered to your door: Winter Soldier Arm (Chrome Plated)
In this part, I’ll cover the 2 things I get asked about most: Chrome and Fiberglass Flanges.
The raw castings are made from Smooth-On ONYX urethane resin. These come out glossy smooth for the most part, but there is still some excess resin (flashing) that needs to be removed to make them wearable. I use a rotary tool cut-off bit to chop out the ends of both the forearm and bicep pieces, and then a sanding-drum to grind down the rest until I’m happy with the thickness.
Once that’s done, I use a cut-off disk to remove the “cutout” portion of the Forearm, being very careful to make the cut as clean as possible. It just so happens that chrome plating will add back almost exactly as much material as a reinforced cut-off disk will remove. Any excess removal of resin will result in empty space, although that’s not the end of the world – I designed the “cutout” to be removed along existing detail lines, so any mistakes here can easily be hidden if needed.
There are a few places where the silicone had some minor issues like bubbles or surface imperfections that transfer to the resin castings. Most of these I just wet-sand with 500 grit paper, though a few need some spot putty first. Because I chrome plate these, any materials used need to be either catalyzed (like bondo), or something that is non-reactive once cured. Spot putty is safe, but only when applied very thin (as directed on the label). Then it’s off to chrome!
I take all my parts to Artcraft Plating in Burbank, California. The owner, Jim, has been working with the film industry for over 30 years in addition to putting chrome on parts for lesser-known entities like Lockheed Martin and the US Army, and he’s a wizard.
I’ll try not to bore you with the details, but the basic process starts with a toxic bath that chemically bonds copper to the plastic. This gives the part an electrically conductive surface. The copper can then be electroplated with nickel, which gives it the smooth, glossy look. The nickel is then usually plated with a third metal. This used to be chromium (real, genuine chrome), but Artcraft has since upgraded to rhodium (since chrome is incredibly toxic). This makes pieces brighter, stronger, scratch-resistant, and immune to tarnish or rust.
(Photo is of Ant-Man, but the copper plating is the same.)
It’s important to point out that a finished Arm is coated with a skin of real metal – it’s not paint, a surface treatment, or anything else. It’s real metal. The skin is only about as thick as a piece of construction paper, and only adds about a pound of weight – a finished Arm still weighs less than 4 lbs – but it adds a ton of strength. That means I can make the urethane incredibly thin. I’ve completely removed the resin from portions of chrome plated parts, leaving just the metal layer, without affecting the structure or stability at all.
I’ve worked with Artcraft Plating enough now that we have 4 different finishes for the Arm, each with a different look: Polished, Satin, Brushed Metal, and a new one we just developed together he’s calling Bright Satin. Bright Satin is my personal favorite, and the one I think captures the look of the “real” Arm best, though the brushed metal look is a close second.
Here’s a comparison of Satin vs Polished.
After the Arm is chromed, I add fiberglass flanges to the Forearm “cutout” and elbow “break.” First, I epoxy several rare-earth magnets to the part of the Arm that will not have flanges attached. I like JB Weld KwickWeld for this – it’s a steel reinforced epoxy that sets to usable strength in about 5 minutes. After the epoxy sets, I brush a layer of wax over the magnets as well as anywhere I don’t want the flange to stick. In this case, that’s the Forearm piece itself – the “cutout” and Bicep stay clean, since I want the flanges to stay attached to them. The wax acts as a release, which is key to the next part.
Each magnet that was epoxied in place gets a mate dropped in place over the wax. The parts then get aligned and held together with copious amounts of masking tape. Then I brush in a thin coat of fiberglass laminating resin (typically polyester, like you’d get at the hardware store). A neat trick I learned from my friend Frank Ippolito is to add in some loose chopped strand fiberglass, which you can buy, or make yourself by cutting the loose edges off fiberglass cloth. I mix this into the resin until its a runny peanut butter consistency. It makes the resin act almost like a gel coat, and makes the areas around the magnets much stronger than they would be as just resin. I back this with 2 layers of fiberglass cloth.
While I have no photos of this process (it’s pretty messy), I did live-stream it on Twitch, and the entire multi-hour session is now on my YouTube channel as a serious of very long videos! They’re also a good look at the difference between Polished and Satin chrome as it actually moves. I hope to find time edit them down, but for now they remain raw and uncut.
Once the fiberglass has cured, the pieces can be cracked apart. Note this will literally sound like they are cracking apart – it was terrifying the first few times I did it! But if you applied wax to all the surfaces you put fiberglass on, they will separate. The fiberglass will hold onto one half of the magnet pair in the newly made fiberglass flange, and the other magnet stays securely epoxied to the chrome. This fiberglass flange will match exactly with the inner surface of the Arm, and once trimmed and sanded will lock smoothly in place with an audible “click” of the magnets.
These flanges secure the Bicep to the Forearm strongly enough I can hold the entire Arm by the wrist without fear of it falling apart. This way, the Arm is much easier to put on – just remove the Forearm “cutout” and re-insert it once your arm is inside – and the entire Arm can be “locked” into a single, seamless piece for photos.
Because the skin of the Arm is real metal, I clean off all the excess fiberglass and resin with acetone. Once clean, I spray both the inside and outside of the flanges with matte black automotive primer – I’ve found this to be the most inconspicuous finish for them, even when they’re exposed at the elbow. I don’t bother to do more than a quick job of masking – any overspray wipes off with more acetone.
Then I spend some time with a pile of clean paper towels and more acetone, and polish the Arm until it’s clear of any resin, paint, or fingerprints. The red star is masked off with Tamiya tape ( I tack a paper pattern in place and tape around it), and painted directly onto the chrome using Red Duplicolor Metalcast Paint. A simple elastic harness is velcroed into the arm at the top of the shoulder and front of the bicep to keep it in place, and it’s fully wearable!
In Part 3, I’ll cover making the Fingers and Hand-Plates.
The Winter Soldier Arm is the most time-intensive piece I’ve ever made. So much so, I don’t accurately know the number of man-hours put into it – it’s somewhere over 300 hours (I’ll get to that later)! I was commissioned to make a wearable piece for cosplay and photography that replicated, as accurately as possible, the cybernetic arm seen in Marvel Studios’ Captain America: The Winter Soldier. Since the Arm seen in the movie was almost entirely CGI, I had to find a way to capture the look, without killing the client or making the Arm unwearable. The final Arm is 3 pieces of chrome-plated, cast resin, with a “break” at the elbow,and another slotted piece in the forearm so it can be put on more easily while still being form fitting.
But before I get into this: if you’re more interested in buying one of these than reading about how I made it in the first place, I’ve got you covered!
Now, on to the write-up!
I started by taking a mold of the client’s arm in plaster bandages. Together, we tried to imagine the poses he’d be most likely to want for photos, and found a position for his arm that would work with as many of those poses as possible. Then I slush-cast a resin positive to use as a base for sculpting.
The goal of the first round of sculpting was to bulk out the arm, both so the client would have enough space INSIDE the final casting to be relatively comfortable, and to build the musculature seen in the movie. The idea was to get all the musculature and shapes correct first, in the clay sculpt, before adding all the complex cutouts and inlays that make it identifiable as the Winter Soldier. I used Monster Clay for this, since it’s easy to work with and I have a pile of it from a previous project. In order to make sure I kept a uniform thickness over the arm, especially in places that needed more room for movement (like the elbow and biceps), I glued down layered squares of plastic so that I’d have immediate feedback if I tried to scrape the clay too thin. This turned out to be really helpful during sculpting.
Once I thought I was happy with the size and shape of the clay Arm, I made a second mold, this time using Smooth-On Rebound 25 brushable silicone, with a fiberglass mold jacket. I made this mold really thin, much thinner than I’d ever tried before, because I only needed one good cast from it and it was a BIG mold (my client happened to be exactly the same size as me – a lanky 6’4″). The silicone is only about 1/8″ thick, but worked perfectly fine for the 2 castings I made.
I slush-cast a pair of positives from this new mold so that I’d have a solid base on which to start building all the details of the “real” arm. (The first casting was far too thin in places and bent easily, so I made a second, sturdier casting.) Once I had a good resin copy, I realized I wanted certain areas to be bulkier – so I sculpted more mass onto the cast using Apoxie Sculpt (a 2 part clay that hardens into plastic when dry). That turned out to still not be enough, but I was out of Apoxie Sculpt so I switched to Smooth-On Free Form Air – a true epoxy putty. The Free Form Air turned out to be a good choice – it sands much faster than Apoxie Sculpt (and in this case it didn’t matter that it’s very porous – something that normally makes it a less ideal choice for sculpting).
At this point I still wasn’t sure how I was going to add in all the detail lines on the forearm section, so I made the entire Arm smooth. Some bondo and spot putty and sanding, then a pass of rattle-can primer to check the overall shapes, and finally several layers of high-build catalyzed primer. This was also the debut of my “spray booth” – the Arm was just too big to spray without hanging, and I didn’t want to be blasting primer all over my shop. The booth won’t pass any inspections, but it gets the job done!
Finally it was time to start adding in all those details! I’d decided to do this by adding layers to the Arm, as opposed to taking material away, because it seemed the most straightforward way to keep the muscles and shapes I’d sculpted already. I had some scraps of a rubberized spandex – a 4-way stretch material with a glossy outer coating. I glued 2 layers of this to the Arm with Super 77 spray adhesive, and cleaned up the seams as best I could. Then I went to work tracing out the accent lines in exacting detail (I’d already done this once, on the first cast of the muscled Arm, before realizing I needed to make alterations and would be painting over it anyway).
Once everything was patterned out, I used an X-Acto knife to cut away the various layers. This was where I learned that urethane primer sticks to things far better than standard Krylon does – I had several areas where the spandex lifted both layers of primer right off the arm when I removed it. Which cased me more headache later when I had to make those areas glossy smooth. Again.
The edges of the fabric were still somewhat “fuzzy”, so I spread thin cyanoacrilate (superglue) along all the edges since CA will react with spandex and make it hard. (CA comes in thin, medium, and thick viscosity – sometimes called fast, regular, and slow – which is really handy). Then I primed the forearm again with more of my favorite Krylon Ruddy Brown and trimmed, sanded, and cleaned up as much of the fabric edges as possible, using the primer mainly to look for consistency and smoothness.
Then I sprayed the entire arm with a few more passes of urethane primer (standard, not high-build, though even that is several times thicker than rattle-can primer). Sprayed on “wet” it will actually dry glossy, with an egg-shell like texture. This primer was sanded until smooth, which took several days.
I was less than a week away from the client’s deadline at this point, so my amazing girlfriend Miss Kit Quinn stepped in and spent many sleepless nights with me, sanding tiny, tiny details. Somewhere during this time I passed 250 hours of work on my own, and simply stopped counting (which is why I don’t know the exact total, but I estimate over 300). I also fell in love with the “sanding sticks” a local hobby shop carries – they’re small foam and plastic sticks roughly 1/8″ wide that come in various grits, from 80 to 220. They were indispensable in cleaning up all the recessed accent lines.
When the forearm was done, the accent lines for the biceps / shoulder region were drawn in. Because I had so much primer build up, I was able to carve the accent lines for the shoulder directly into the paint. I first traced the lines with an X-Acto, which gave me a guide-line to follow, and then went back over those lines using a combination of a triangle file, and a small, broken hack-saw blade (you never know what you’ll find a use for). It was tedious, and made for some interesting blisters, but effective.
After a couple more passes of Krylon primer and some touch-up with spot putty, the entire arm was wet sanded up to 1000 grit, then cut in half along the elbow. I wanted to mold each half separately, since it would eventually be 2 pieces to be worn, and it made more sense to simply cast it that way (plus, having tried to slush cast the first two versions of the Arm as a single piece, I new I didn’t want to try doing it again!). I made the cut using a full-size hacksaw blade I’d removed from the saw. Since the Arm was hollow, it was easy enough to do, and gave me more delicate control than a Dremel would.
I actually molded both sections of the Arm twice.
The first attempt, I made a pair of matrix molds – these turned out terrible. They didn’t seat right, locked around the Arm, and were generally a huge pain to deal with. I was able to get 2 successful castings out of them after 5 or 6 attempts. Both were cast in Smooth-On ONYX resin. One of those castings was trimmed, sanded, primed, base coated gloss black, and finished with Alclad “chrome” paint. This was the first Arm I presented to the Client.
However, the intent had always been to have the Arm chrome-plated. So after the convention, I spoke to my client, got some feedback about size, shape, and fit, and modified a casting from the first mold to meet the new specs (this was the second casting mentioned earlier). I added more room in the elbow, and made the entire forearm larger, but cutting, the heat-forming / stretching the cast, and inserting layers of sintra and styrene plastic to fill the gap.
Then it was on to more cleanup. With a hard, resin casting to work with, I decided to completely eliminate all traces of the fabric edges that had still managed to creep into the first version. After more primer, more sanding, more help from Kit, and many more sleepless nights, I finally painted both sections of the arm in glossy paint, wet sanded them to 2000 grit, polished them with rubbing compound, and finally buffed them with wax. I wanted them to come out of the mold glossy and ready for chrome.
This time, I used Rebound 25 and made brush-on molds for each section of the Arm, with fiberglass mold jackets. These came out excellent, and have been serving me well since.
Casts are slush-cast in Smooth-On ONXY resin.
In Part 2, I’ll talk about getting the Arm plated with real metal chrome and adding magnetic flanges to hold it all together!