Missy, which type of plastic are you referring to? I typically think of the clear mylar when I think of stencils, and I can give you some sources for that, but know that the craft stores also carry stencils with that thicker plastic, and I'm at a loss as to where to find larger pieces of that.
If it is mylar you want, quite a few stencil designers carry it in various size sheets. Off the top of my head, I would check with Mad Stencilist or Designer Stencils (see
Stencil Designers page for links).
You can also puchase larger quantities in a roll. I have ordered in the past from this company:
Continental Milano Imaging Products
1-800-237-7347
<a href="
http://www.milanoinc.com>www.milanoinc.com[/url].
