Like I posted below, you can make an improvised "face shield" out of plastic food wrap in about 15 seconds. No parts needed. Wrap it around your head at forehead level so it sticks to itself. Keep the bottom part loose, so you can freely breathe.

Readily available, cheap, disposable, lightweight, does not restrict visibility.

If you're working in the wind, you might need to weigh down the bottom part with something, but that's also trivial to do.