Is the template for tracing around so that you can then follow a pencil line? Card stock should be fine. Is it a picture that you want to follow similar to how many folks do on a scrollsaw? I print things on my computer printer using regular paper, use a spray adhesive and stick the picture to the material. A heat gun makes removing the remaining paper easy. Is it a template to be used over an over again for years? 1/4" MDF works well for this. As stated, better info yields better answers . Let's talk some more.
Any sufficiently advanced technology is indistinguishable from magic.
- Arthur C. Clarke