Copy-Void printout: How?

How to create a print design that says VOID when copied

[ngentot]

Have you all seen a check or other printed valuable documents that say VOID when people try to make a photocopy of? How can I do that with Photoshop? I'm trying to design a gift certificate with this security feature.

Thanks.

[Abdelrhman Fahmy]

i tried to search for you and found that it's about the printing papers ,i'm still searching because i'm interested about it also but you may need to review this

[tonerlogic.com...]

[protectedimages.com...]

[Abdelrhman Fahmy]

i think this will help :

[1st-copyright-security-paper.com...]