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there are a number of threads on this. basically NS isnt going to sell them. instead theyve put up some stencils for you to make your own one if your feeling up to the satisfying pastime that is arts and crafts.
If you're scared of the fumes in spray paint just get creative with acrylics. Get a few different colors and go to town. You don't spray the stuff but you can still use a stencil plus acrylics tend to give more even coverage if you take the time. If you need an idea for your stencil just look in the upper left corner of the page and get started.