kitronik shares how to add LEDs to Easter bunny ears on instructables.
A miniature cell holder is just the right size to be hidden away under the headband along with a small slide switch that allows you to turn the ears on and off easily.
The project requires advanced skills as there are two separate sets of LEDs on each ear, all of which are controlled by one cell holder and switch.
This circuit is slightly more complex due to the shape of the headband: stitching the circuit is quite a fiddly process. Use the diagram along with the instructions to help you understand how the circuit is integrated into the product.