Figure out where the wires need to go through the inner mirror. Mark the spot and cut a small opening.

Then insert the NeoPixel strip into the lid. Glue the cardstock tabs to the sides to hold the lights in place.

Crafts sticks wedged in between the strip and the lid will hold the tabs in place while they dry.

To attach the Gemma to the back of the inner mirror, stack a few reusable adhesive squares on the back of the board. This will give the board enough height to allow for the alligator clips.

Use more squares to attach the battery pack, with the on/off switch facing up.

The squares should make it easier to remove the battery holder to put in fresh batteries. Remove it slowly to minimize tears to the cardstock.

When the glue holding the NeoPixel strip to the lid is dry, carefully pull the alligator clips through the hole in the inner mirror. Then insert the inner mirror into the lid. Let it rest on the edge of the light strip sheathing.

Glue small rectangles of cardboard above the inner mirror to hold it in place. You can still slide it out if you need to.