Okay!  

I’ve received so many questions about how I made this arm.  I got the idea from this lovely robo arm and as it turned out, she also used the same base pattern that I had planned to (Edward Elric’s automail arm).

Basically what I did was take the pattern and heavily alter the arm pieces while keeping the hand mostly the same.  I used mostly craft foam combined with leftover styrene I had from a different prop project, and three different size brads (from the scrap-booking section of Michaels). I glued everything together with high temp hot glue, but I sealed the finger pieces with e6000 at the seams to ensure that they wouldn’t pop open in hot weather.  Once I had all my parts glued together, I coated them in about seven layers of Mod Podge cut by half with water.  Once this was done, I coated all pieces in Plasti-Dip spray (it’s a rubber coating that you can get at Home Depot near where the spray paint is).  Since I wanted the arm to ultimately look used and abused, I made sure my spray wasn’t perfectly even - just don’t overspray or you’ll lose some of your detail.  When this was dry, I added the brads and painted over them with black acrylic paint.  

I covered each piece first with silver Rub n Buff - again, acquired at Michael’s.  Then I did washes and dry brush layers of black, brown, and orange with some additional green Rub n Buff antiquing wax.  I started with the idea of making the rust look natural but got lazy halfway through.  

The forearm closes with velcro, hot glued in place.  The upper arm doesn’t open, it just slides on and stays.  I accidentally made the arm smaller than I’d wanted to so it’s a tight enough fit that the pieces don’t slide around.  The wiring between the joints is held in with duct tape, and only attached at one end, so it moves in and out as I flex my arm and wrist.  The hand piece slides on.  I wore a full-arm length glove under the arm to improve the aesthetic and for comfort.  

I hope I covered everything.  Let me know if there are any questions and good luck!