Here is the making of for my award-winning Alphonse Elric cosplay. It took me 6 months, and was very taxing and very fun.
[ Black 3.0 ]
Stuart Semple's black 3.0 is the blackest acrylic paint around, absorbing 99% of light. It really is super matte, and looks like a void. As luck would have it, the kickstarter ended right on time for me to get my hands on it, and I painted the inside of the collar. The effect is stunning, the helmet really looks like it's floating on an empty suit of armor!
[ Stomping fx ]
I wrote a small tool for stomping sfx on a regular smartphone. You can get it at https://github.com/castpixel/STOMP
How to use: open the project using Construct 3 and run it. Feel free to change the sound files and reference those instead.
When you run the tool, shake the device vigorously to calibrate it to max acceleration in all three axes.
Dragging the indicators changes horizontal and vertical sensitivity. That's it. Strap it to your upper torso and walk.