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paper protection?

how can i make: 1) photo-copy evident protection (when photo-copied will show void) 2) how can i make special markings such as are on official documents and store gift cards by myself to protect my documents ?

Nofew8 years ago
I'm not totally sure, these are just my best guesses from personal experience. 1) Use high gloss paper in a scanner, it'll be white then. There's no way other than covering up a paper with something if the person's using a camera with flash turned off, though. 2) Watermarks. Google it. If you're really paranoid, try invisible ink. I think there's an instructable here on how to make it.