Annnnnd, we're done. Thank you to everyone for playing, but I've locked this thread to further comments.
Our rules are subtle, but clear enough if you try to understand them. Basically we don't give help on how to hurt other people, but the O.P. probably wouldn't care even if it were pointed out.
We frequently get questions on how to maim, annoy, hurt, incapacitate, kill other people with this magic reagent or that magic process. And there have always been technical solutions to these problems that never work, like the a fore mentioned lights or cameras, so how is the chemical going to be dispensed? People need to defend themselves against pirates, or dissolve a rock in front of their door, when a mundane solution, like a gun or a crowbar would work just as well, or not any better. So what does this thread matter?
Simple. The O.P. wanted to make a racist rant, because elsewhere on the internet, this would be met with a chorus of "Oh yeah, I feels for ya bro. Try some aqua regia, you'll get all that Gypsy gold afterward." Well ... not here.
Let me depress you further Aery:, the Romanni are humans. And by definition, for all humans on this planet, our nature is to be crafty. You may have convinced yourself that they're going to be mystified by some random technique, but they have Google capable phones too. And they'll just turn your trick against you.