This is for use with the [PET Bottle Rig](http://publiclaboratory.org/wiki/pet-bottle-rubber-band-rig) Instead of using a balled up piece of tape, a pebble, or some other thing to hold down my camera's shutter, I've gone to using a knot. This makes it easy to hold in place, and makes setting it easier. I prefer [a rubber band](http://publiclaboratory.org/wiki/rubber-bands), but tape also holds it down. tape may be more useful for bulging, non rectangular cameras. My Canon SD1000 needs the [rubber band](http://publiclaboratory.org/wiki/rubber-bands) tripled up to hold it in place: knot+rubberband+continuous shot = easier than CDHK knot+rubberband+continuous shot = easier than CDHK knot for shutter with tape source: http://publiclaboratory.org/notes/mathew/1-29-2012/using-knot-trigger-cameras