I started with another big Dollar Store purchase. Led spotlights. You can even get them with seasonal caps on them and remove the lids. I ended up getting what is often called or called fairy lights.
These special sets were a little more expensive than you can find in the dollar store … but worth it because they each had 6-On-18-Off hours built in. Plus each one was colored to the corresponding color that I wanted to match to each night light.
I fed the light wires all the way and then I mounted the battery pack on the underside of the back of the box with a little double duct tape.
With this set, I then attach the strings of light around the inside of the front of the box. Use smaller pieces of duplex duct tape to place them roughly. Then I did a facial light test and placed each face over each color with my back over the illuminated box to see if I needed to reposition light for good coverage.
After I was satisfied with the light balance around the edge, I put drops of hot glue over the threads to keep them securely positioned.