Stencils are printed as masks or screens. You lay the stencil down on the surface you want to paint, and run the ink over the stencil; it goes through the holes in the stencil and paints the surface. The stencil is removed, and in a multi-screen process, the surface being printed on is shifted to the next stencil in question. Adobe Illustrator’s Live Trace function allows vector-based stencils to be made easily from raster artwork, including a scanned photo. Writer Bio

How to Turn a Photo Into a Stencil in Illustrator - 73