I could easily print up a bunch of stickers. My vinyl printer is begging for more jobs to run through it. That's a pretty good idea. I'll throw it on the front burner!
And your strategy is exactly my own. I've got 3 types of tamper proof fasteners holding my Beatrush latches in place. I sell the square nuts. Another is a pretty common security fastener. And I won't sell the last because it's just for me.