A few pics of how I do LED eyes. The eye color is printed out and glued to the eye blank, then an LED is inserted and glued to the eye. I solder on wires and resistors to adjust the voltage and current for the power source. I use a small USB power bank, so these LED's run off 5v. Using the USB battery bank makes it easy to remove from the head and recharge. Once the eyes are mounted to the head, I add the eye lids, which really change the look of the eyes a lot.