3D Printing and Surface Preparation

As luck would have it, I was able to source an excellent 3D model online for the automail and skip the modeling step entirely. Even more luckily, the parts fit me perfectly without having to do any resizing.

All parts were 3D printed with PLA plastic, and the parts that were subdivided in the model (chest piece, forearm, upper arm, and small shoulder plate) were super glued together. Seams were filled with super glue + accelerant then sanded back flat. Small gaps in the print were filled with Bondo, then the whole raw print was sanded to removed layer lines with 90 grit. It was then smoothened up to 400 grit before priming.

The pieces were then primed with 4 coats Rustoleum white primer - extra coats were added because this would be sanded back a bit. I selected a white primer so the later graphite coating would have lighter note versus the typical gloss black undercoating. After the primer fully cured, the surface was polished with 1000 grit sandpaper to a nearly reflective smoothness.

Graphite Powder Coating

Ever in search for a realistic metal finish, I experimented with graphite powder coating for these pieces. Rubbing graphite powder onto a polished surface creates an incredibly realistic metal finish, however it is a delicate coating that slowly rubs off with handling and easily picks up and shows skin oils. I tested a few different clear coats, and only the water-based coating (Pledge Floor Finish) did not interact with the graphite. I suspect this is because the other coatings were solvent-based paints. These solvents are all hydrocarbon liquids, which are non-polar chemicals. Graphite is pure carbon which is also non-polar so they are prone to interact. Water is a polar molecule, and under the same principle that prevents water and oil from mixing, it didn’t interact with the graphite coating. Likely any other water-based clear coat would work as well.

The clear coat does impact the shine of the metal under certain lightings. In most cases, it looks exactly like the original graphite powder coat, but under angled and low-lighting the plastic-y gloss stands out more than the graphite. I found this pretty insignificant though and would take the trade-off for the protection the clear coat gives.

All of the pieces were covered in a layer of graphite powder, applied by taking a cotton ball, dipping it in the graphite powder, then buffing it into the surface until the graphite was thickly rubbed in. Continuing to buff with the cotton ball continues to improve the reflectivity up to a very convincing metal shine. Following this, the pieces were all covered with Pledge Floor Finish. This was before I acquired my airbrush, so the Floor Finish was was simply poured over, being sure to cover every part of the graphite surface and letting the excess drip off. The final coating thinned out pretty well on its own, though an airbrush coating would probably be preferable. The pieces were allowed to fully dry before assembly.

Rigging and Detailing

To create the illusion of a prosthetic metal arm, the armor pieces are worn over black cloth skin-tight garments.

The glove was done as a separate piece, with each of the glove pieces glued to a black stretchy glove (see first video for final result and range of movement).

The chest piece was affixed to a black spandex sleeve, cut out from a morphsuit. To make the shoulder articulate properly, holes were drilled into the part of the chest piece immediately behind the faux rivets where the shoulder should sit. Small metal dowels were glued to the shoulder behind the rivets, through the holes in the chest piece such that the shoulder freely pivots on this axis.

To wear the chest piece snugly, a securing belt was installed. Two strips of wide nylon cloth were glued to the inner side chest - one in front and one back. The back cloth strip is sewn to metal D-ring belt loops. When putting on the chest piece the belt is tightened around my upper torso to hold it in position.

A thin brass bar was bent to shape and installed in the armpit area of the chest piece. Cosmetic red and blue wires were glued along the length of the sleeve, hiding the glue underneath the other armor pieces.

The upper arm and forearm pieces are not affixed to the black sleeve, and are simply slipped onto the arm once the chest piece is secured in place. The glove is then put on last.

The second video shows the full movement of the armor and final result when worn.