I bought a face shield from Lowes and slapped some window tint on it. Applying the tint takes some patience and a few retries, but it turned out pretty nice.
I used a dremel to cut it after making a cardboard template and testing the fit. I suppose a jig saw would work just as well. I actually cut my tint to the shape of the t-visor and applied it last.
I just used a pair of heavy duty scissors to cut out the visor, had no issues and trimming was less stressful... though my safety shield may have not been polycarbonate:confused it has flex to it...