It's gonna have: a blue led light and a blue laser coming out of the barrel (that both light up when the trigger is pressed), adjustable autofire, Star Trek (original series, of course) phaser sound effects (again, activated by the trigger), and a port at the base of the handle to detach the zapper cable.
I've already built a working one that has the blue led and sound effects. Just gotta add autofire, laser, and the detachable cable.