I don't know if that's possible but is there a way to make something like a custom playable character model?

How do I make item mods? I want to make item mods, but I have no idea how to do it. I would appreciate an explanation on how the character editor works, too.
I found no tutorials online about these.

The idea is simple: if you go to a high-pressure zone without a diving suit and survive you become completely deaf for the rest of the round.