From slashdot: The Solar Death Ray.

Quoting the "about" section:
Quote:
The Solar Death Ray is made of 112 mirrors mounted on a platform 4 feet
wide and 6 feet tall. Each mirror is a square roughly 3.5 inches on edge. All
these mirrors focus the sun to a single spot 5 feet, 6 inches from the mirror
platform. A wooden fork extends from the mirror base to the area near the
focus and serves as a mounting point for Solar Death Ray targets. The
mirror platform is mounted to the support frame on a pivot that allows the
platform to be angled. The whole system is mounted on a set of wheels.


So if everyone in your party has a signal mirror... :-) :-)