Here is my version of quantum splicer used by Firestorm in The Flash TV show. It's designed to for 3mm LED and CR2032 3V battery.
Connect 4 x 3mm LED in parallel and one one of the arms there is rectangle slot for micro on/off switch.
I printed the red LED cases in translucent red resin on my DLP printer but you can use clear PLA or translucent HD Glass and print it on FDM printer.
On rest of the arm there are holes for mini brooch back bars pins so you can easy attache the device to your t-shirt.
Physics, 3D printing, Programming, Astronomy and Sci-fi - that's me \//