In my pursuit of updating my TMNT figures, I saw my metalhead, and always wanted his eyes and brain to light up. So I cracked open his shell, Drilled up from the bottom peg, and attached a LED light into it. I wanted to be able to change his batteries when I wanted so I carved into his backpack and put in a battery holder for two small watch batteries. On the side I soddered on a switch to turn it on and off.