ever see these stupid things at your local dollar store? They're called finger lights and come 3 to a pack for a dollar (duh). You get a red, a green, and a blue. The best part is, they fit almost perfectly inside Meg's arm cannon, with minimal trimming inside. I completely took out the blade gimmick, removed the little power pack for the old light, and it basically just sat right inside. Not sure how well it will work with the blades still in, but it works perfect without, and even gives a cool little glow on the outside. I might hit it with some clear blue paint to make it glow purple now, and secure it a little better to prevent light leakage. I did make use of the original battery door, it is turned upside down inside the cannon to give the finger light exactly enough boost to sit flush with the rest of the arm cannon.