Where can I find food grade blank stencil sheets that are 10mil. I been looking everywhere and I cant find any :(

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do you think .007in is going to be thick enough?

No idea about how thick they are but you could try cutting up a plastic document holder/file. Like this one: http://www.amazon.com/dp/B004Q9Z9FW/?tag=cakecentral-20 

Food safe? You wouldn't want to eat it but if it is in contact with your cake for a few minutes while you smear royal icing over it, I personally wouldn't worry about it too much. 

You can buy acetate sheets used for chocolate (so presumably food safe) from pastrychef.com or jb prince or other outlets that carry baking type products. You can also buy the sheets from art supply stores like Dick Blick, etc...

Good luck!

RJ