I needed to add LED lighting to my Prusa i3 Mk2 in order to see the bed with Octoprint and a camera better. I designed this set of two brackets and a single bar for LED strip lights that I had left over from another project. The exact lights I used are these:
Bang good non-waterproof LED strip light, 12V
The LED bar can be printed on the Prusa bed by rotating 45 degrees. The bar and brackets are circular so that the angle of the strip can be adjusted to an extent, to best light the bed. The lights can be mounted with a single bracket, but at least two provides greatest stability. They were printed using the standard PLA settings that come with the printer. NOTE: Some LED strip lights can get quite hot over time, so consider printing in PETG if needed. I'd also recommended gluing the edges of the LED strip into the bar with superglue or epoxy, as the sticky-backing isn't usually that great.
The brackets should be mounted to the BACK of the printer, in order to remain out of the way of the print head when it's raised to the top.
For my own setup, I used the two remaining wire connectors in the Mk2 power supply to provide the 12V power to the LEDs. This required taking apart the bottom of the existing power supply, so make this modification at your own risk! I also added an in-line switch to turn the lights on or off separately from the printer. Using a separate 12V power supply for the LEDs could easily accomplish the same thing.
No need for supports or rafts, brackets should fit snug to the metal bar at the top of the printer.