Materials:
Thumb button off a knife blade
Dremel
Drill and small bit
Bench Vise
I simple unscrewed the thumb button from a knife blade I had lying around. I used the threaded shank portion. I drilled a hole in the safety lever and pressed the button into the hole using the bench vise. I cut off the threaded portion that wasn't needed and smashed it with vise grips like a rivet. The bench vise would have worked for that as well. The thumb lever is somewhat wobbly by design so sometimes it's a bit tough to position the lever from Fire to Safe, but there is NO difficulty moving it from Safe to Fire, which was my ultimate goal. I shoot two-handed, so my supporting hand will position the safety from Fire to Safe if need be. The back side of the button slightly rubs the slide where the red dot is, but I don't care on this $180 gun. As long as it does what I want, I am not really concerned. This is practically a tackle box gun, able to get beat up and dirty without hurting my feelings.
Result:

Thanks for looking!