Back in the early 90s, we used to use the fan system found on ski-goggles called "Turbo Fan". It was tiny, and fit partially inside the mask.
But seeing the penis-pump idea, I wonder if it would be feasible to use air, diverted from your hpa/co2 tank to wick the moisture off the lense.
I could imagine a simple t-fitting, hooked to a simple on/off valve that could be turned on slightly enough to blow air through a hose into a mask.
If that worked well enough, and had money to burn, you could utilize a lpr with solenoid setup, and quick-disconnectes, etc. WHy not?
NOt sure about co2 though. Since it tends to be colder, it might cause the outside of the lense to condense moisture... making things worse
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