The Cyborg Implant of K.T. from the new Bloodshot Movie.
Just print the main "breather" part in a flexible Filament, paint it and attach it with a skin save adhesive. Or you can print the "negative" mold to cast your own silicon or latex prosthetic.
Since this is not really connected to a cybernetic lung, it won't help you against any gas attacks but it's a cool accessory for fans of the Bloodshot movie or anyone else who likes bad-ass cyber-implants.