Lasersabre

A lightsabre: the most vicious weapon in the galaxy... Well, we haven't even invented a way to get to mars, or another galaxy, so this will be an alternative weapon. It is a laser, a pipe, 2 mirrors (1 semi silvered mirror and 1 normal mirror,) a solar energy cell and a piece of curved plexiglass. Connect the pipe to the laser. Then place the plexiglass on the pipe so it will make a curve around the laser's beam. Attach the solar receptors to the plexiglass, so that when the laser fires, it will 'catch' the light so that you have an unlimited supply of energy. Then, place the normal mirror at the end of the pipe so that it faces perfectly at the laser, and attach the semi-silvered mirror to the laser's lens so that the laser light will go out, but not back into the lens, which will make the laser explode. So then just flick the laser's power source to get it started. (The solar battery will have to be pre-charged to make it work.) Get it. The only downside is that only 1 half of the laser will slice thru anything. You could always sharpen the plexiglass, but that might complicate things with the solar cells. Try to picture what it will look like.