I was thinking of getting a wooden ruler and carving little grooves into the long edge of the ruler, then drag the carved edge lengthwise across the string, so that it plays a little etched "sample" by rubbing it against a muted string.
I don't know if it'll work well but the results should be interesting regardless.
I also fitted a selectable push button kill switch to my guitar, so a combination of the two would be possible.
I want to start a live noise project where we set up and play in a tent and blast noise out to people whilst they wonder what the hell we're doing inside the tent.