Halftone Stencilling

Many graffiti stencils are based on images that have just been processed at a threshold for lightness. You might say they're "plotter" style stencils. I imagine another approach somewhere between "dot matrix" and "halftone": if you have a tool for making holes of one size, you can create darker areas by concentrating the holes. Borrowing from traditional color printing techniques, if you create three stencils for red, green and blue, you can produce a "full color" image. It would be good to automate the hole placement, or even choose aesthetically pleasing dithering algorithms.

This idea comes from a stencil I saw in Rome last night that used the kind of line art we have for the portraits on American currency. We might as well experiment with other approaches to stencil creation and construction as well.