Ed’s Automail Arm – Step by Step

 

By request, here’s the step by step process of how I made Ed’s Automail. There will be a few gaps in the photos, as I wasn’t doing the best job of chronicling this build. I’ll try my best to fill in the image gaps with adequate words.

Since there was no way to meet with my client and make a mold of his arm, I got several dozen measurements from my client and stitched a plush replica of his arm in muslin. I also made several paper mockups at this stage of major parts and mailed copies to my client to hold to the appropriate areas on his arm and hands and take photos so I could verify fit and scaling before moving to making the pieces in woderflex.

 

To make the end caps for the fingers, I coated a it of PVC pipe the same diameter as my client’s largest finger with bondo and began shaping the cap.

 

The pipe was cut off and the bottom sanded. You can see here how tiny my hands are compared to my client. I have very small hands, so the plush arm/hand double was vital to making this automail. After I sanded the piece carefully, it got several clearcoats and went under silicone. I then cast five copies using black tinted resin with Smooth On’s cast magic powder in Silver Bullet.

 

For certain areas, I wanted to use silver metallic stretch vinyl in order to minimize how much this automail would restrict my client’s movement. Here is the cold cast resin finger cap next to the vinyl, the finish really is very similar.

 

After getting the confirmation that my paper mockups were the correct size, I started the somewhat tedious process of cutting out all of the pieces. Each piece was numbered to keep them straight, I ultimately had to cut out two dozen pieces in Wonderflex and keep straight probably three dozen resin castings, so numbering was vital. Each Wonderflex piece was double thickness, one layer was just going to be way too flimsy. Once cut, the layered were joined with some mild heat from the heat gun. The folks over at The Engineer Guy are my favorite source for Wonderflex.

 

Once the pieces were layered, it was time to form them. I recruited pretty much every wine bottle, storage jar and tin can I could find to get the right curve forms, and even used my own thigh for the upper arm plates, as it turns out it was the perfect size (Shows how tiny I am that my thigh is the same thickness as an average man’s biceps). I used painters tape to keep the wonderflex in place while it cools. Wonderflex is a very useful material because, once you have applied heat, it remains pliable for about two minutes afterwards, meaning when you handle it, it’s no longer scalding hot. This is a huge advantage for anyone who has had to deal with heat forming styrene, which is only pliable while hot, lots of burned fingers!

 

Here is where I start having gaps in photos, as I got to the point where each piece was at a different stage in the process. Here we see the upper arm plates heat formed and hit with 2-3 coats of primer, which was then sanded. Wonderflex has a slightly pebbled surface on the presentation side, but a few coats of sandable primer usually handles the texture. Another trick for smoothing the surface is to use the back of a spoon  to burnish the surface while the Wonderflex is still pliable from heating.

 

You can also see the elbow piece and some of the cold cast resin pieces. They’ll be used to fill out all of the screws, studs, pivots, knuckle covers and any other little circle bit needed to embellish the finished piece. The elbow piece is also wonderflex, but has had additional buildup with Bondo to create the rounded  form.

 

I also ordered some colored plastic tubing and heat shielding to add in the armpit area to replicate thewiring and tubing. The large screw top there is actually a cast from the mold for my gold circles for my Lightning’s coat, with the notch scored in with the dremel.

 

Here I started assembling the hand plate and started working the finger sections. These are just stretch vinyl cylinders, since if I had cast these in resin or used Wonderflex, my client wouldn’t have been able to fully bend his fingers.

 

A glove will hold all of the pieces in place and hide the client’s skin. It’s sewn in basic black spandex. The paint I used for the silver is Valspar’s metallic silver. It’s not a chrome-like finish, but is far more durable than most of the high quality silver glosses I use, which I felt was very important since this piece would rub on itself and bits of the costume all day. Another advantage is that this paint has a much more forgiving humidity and temperature tolerance, which was an absolute lifesaver in southeast Georgia in June and July!

 

For the large forearm plate, I needed to thicken the wonderflex substantially. So, I cut a lower layer in wonderflex, then cut filler layers with the three dents cut out in EVA foam. This was easy to cut, lightweight and could hold up to the heat-forming of the wonderflex. The blue strips all-over the board are the notches I cut out. I then layers another layer of wonderflex over the base and foam, then pressed in the trenches so that the top layer of wonderflex bonded with the base layer, rounded the edges and flattened the outer form. This is the plate in an early form, after this would come a lot of extra filling and sanding.

 

The piece starting to come together! As you can see, some places required extra puttying and sanding, but on the whole the wonderflex didn’t require too much extra work.

 

Here’s a shot of the plate as I was puttying and sanding it, the pink is bondo, while the grey is Krylon sand-able primer. To get into the trenches I used a combination of sanding sponges, emery boards and standard sandpaper.

 

The hand was finished up with a sewn vinyl half glove. The T-shaped fastener is EVA foam covered in stretch vinyl, and I attached it with heavy duty thread sewing the T to the half glove. The stitches and knots are hidden nicely under the little resin studs. I also attached the finished arm plate to a strip of stretch vinyl for the underside of the forearm. The whole forearm closes with velcro hidden under the plate.

 

Here you can see the full arm underside, and the elbow attachment. The elbow also has a strip of stretch vinyl which will give more comfort when my client bends his elbow. The upper arm was also finished with a sewn vinyl cover.

 

The complete hand, the only hard parts are on the fingertips, back of the hand and the resin disk on the side of the thumb. This will give my client maximum use of his hand. I also took these final photos before realizing I had forgotten to add the studs to the arm plate, Whoops!! I made sure the studs were attached before it went to the client however.

 

For the shoulder area, I connected the major pivot points with a few real studs, then added all of the extra studs using my resin replicas. I also epoxied in the tubing and heat shielding. The spandex glove pulls all the way up over the shoulder and has a strap that wraps across the chest to keep everything in place.

 

This was a really interesting piece to work on. It used several materials I rarely get to use, but have always loved working with. I can’t guarantee it’ll help with your alchemy or survive a disagreement with your teacher, but at least you should look cool with it. Hopefully this rather messy write-up will help others hoping to tackle the project. I gotta say I have even more respect for Winry after making this!

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