Hi,
I did a bit of research and found that people use "acetate" sheets to make stencils. You can get it from art & craft stores mainly.
Theres a Uk shop and website that sells it -
http://direct.hobbycraft.co.uk/search/acetate
Or if you have a local craft shop and ask if they sell acetate sheets?
Hope this helps, Good Luck! 
There is a tool and sheets specifically designed to make stencils for cake using food grade mylar. I would post the link but that site will be blocked by CC. BUT, if you take the word sugar and put it with the word craft, add a www to the beginning and a dot com at the end you will get to the website. I don't know why they don't sell the same tool at Global Sugar. I have one on order because I have a request for a custom design, I hope it works well!
Jen
I bought stencil paper (it's a flexible plastic) from Michaels and used a pencil to trace the design and my exacto knife to cut out the design (it is the damask cake and cupcake tower in my pics). In all honesty I didn't even consider that it wasn't food grade plastic? It was only in contact with the cake for about 30 seconds.
People use non NSF stuff in their kitchens all the time, but I think its something you can get dinged for by your local HD. There is also a difference between stuff being meant for home preparation and stuff that is approved for commercial food preparation - Example, Cricut Cake... made and marketed for CAKE. But I have heard people getting warnings/fines from their HD because it's not NSF, therefore not appropriate for commercial use so they had to stop using them for their cake businesses.
I have used stencil sheets for painting so I know what you are talking about, but I would not want to use that for a cake, they're not very bendy. Manufactured cake stencils are bendy yet rigid enough to get a clean edge.
But looks like you worked it out OK!
Jen
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