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I have 5 poster signs, a few for backup, ready for construction. I’m placing double edged razor blades at key points where someone would grab the sign. I have them well placed and somewhat “hidden”. Paying close attention and you’ll see them with no problems. Doing a drive by and yanking it in the middle of the night though; well, that might cause a bit of skin to break open. "
why not just put em in your windows? or better yet, anchor the sign to a nearby tree.