Find the LED Light Bar here https://www.prusaprinters.org/prints/3267-led-light-bar-prusa-i3-mk2mk3. This LED Light Bar print does not have a center piece with it. The guide there says to use an aluminum channel to hold the LEDs between the ends, but I wanted to print a solution. Since the distance is longer than will fit on the MK3S+ bed, I made it in two sections that fit together with a little CA glue. I used LED tape that is 9.3mm wide, but the channel will hold up to 11mm.
This center bar fits tightly into the end pieces linked above. Work them in gently and they will fit well.
The author hasn't provided the model origin yet.