The original battery holder by KikiTay was modified to mount 4 LEDs. The final piece was attached to the tip of a violin bow for a live performance of Radioactive, by Imagine Dragons. (The bow looked radioactive.)
I started with the 2x CR2032 holder by KikiTay, and added two extensions to accommodate four LEDs. I modified the interior of each half by filling in the groove for wire and made a wider path for copper tape.