Here is the headphones that I've modified to be awesome.

For this build I was using:
2 bullet shells S&W .40 Cal
old headphones. It happens that mine fit perfect to the bullet shells without any glue. I was using TDK EB760
10mm wooden dowel
sandpaper 400Grit and 800Grit
finishing sponge (You can replace it with high grit sandpaper or steel wool)
a hacksaw
a battery powered drill
a drill bit (diameter of the drill bit should match the diameter of the wire)
a soldering iron
a vice or a clamp to fix the bullet casing for drilling

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