Evil Mad Scientist Laboratories - Quick, easy, temporary, and beautiful LED garden lights: "For a late night summer party, we wanted to deploy an array of maybe 20 or so little LED garden lights along the periphery of our back yard. And since it was for a one-time event, there wasn't much sense in buying (or building) a set of nice looking permanent solar lights. So here is an alternative: make your own ultra-low cost temporary garden lights using LEDs, lithium coin cells, and mason jars."
10 mm diffused white LED
Panasonic CR 2032