When it comes to this question I find it is difficult to truly decide what LED s to use in your saber because you are torn between cost effective price and truly phenomenal color and brightness. The two major options are in hilt LED s and a Neopixel LED strip blade. The in hilt LED uses a LED either composed of single, dual, tri or quad cree dyes to color the LED. While this is easy to wire the science behind it is interesting. You place the LED in a heat resistant housing and place heat resistant tape underneath the LED. In front of the LED a lens is added to focus the LED and make it brighter. to fully complete the LED your saber blade must have a reflective tape and transparent film to evenly light the blade for no dim spots. Now Neopixel blade are incredibly bright but they are a full string of LED s inside the blade that you choose. The wiring is a bit more complicated but if you have the cash and want to make the brightest saber this is the way to go. There are connectors inside the hilt that allow for a connection to be made and light the blade. Pairing up a Neopixel with a Proffieboard is the way to go if you want a saber to be reckoned with. I will be doing more Neopixel builds in the future just to have amazing sabers in my personal collection.