Diy Face Mask

Most of the high quality available masks use NATO 40mm filters or have adapters for them. Even the current 3M 7800 series full face mask supports them. There are different models that are currently available w/ the military that don't but, 40mm is a world standard. The Avon FM50 uses a proprietary bayonet design that gives some really good positive locking, but it's not common so price vs protection isn't quite there. Avon, however, does have...
I wouldn't call any of these high end and the VFC Avalon series is now generally accepted as superior to Krytac at the ~$350 price point nowadays. Also, VFC Avalons go on sale much more often so it is likely a better choice to pursue as Massdrop is more likely to get MAP dropped and therefore a better price.

That said I can't imagine even VFC agreeing to do this as the airsoft industry is fairly closed to this sort of thing and if VFC allowed this...