Various markers use various types of LEDs, both surface mount (SMD) and through-hole, in varying colors and strengths. Here are some of the mods I've performed over the years.
Shocker SFT / Nerve:
Like the stock LED but don't like the blue color? How about these ones instead.
Below is a service I once provided back when my business was first starting. It involved moving the LED to a new spot on the frame. Here's one in red...
Predator SFT boards:
The older versions of the Predator SFT boards (revision-A and revision-B) used dual blue LEDs to pulse during gameplay. I switched mine out with red ones to match my other LED mods on the marker.
Ion:
Here's an example of the popular LED relocation mod.
To go along with that, I also changed the stock programming LEDs to superbright ones, of any desired color (red and blue pictured). This was more of a "just for fun" mod, since the LEDs are only used during programming. I offered this modification for others, but quickly decided to stop it because board adjustment became much more difficult since the colors no longer matched the manual.
Shocker Sport:
LED relocations on these markers is very popular. Here's an example of one using 5-mm superbright blue LEDs (one for power and one for low battery).
Here's a 5-mm superbright red and green LED pair. These are the board indicator LEDs, just moved down to the frame.
Impulse:
This is a similar mod to the Shocker Sport except I remove the stock LED and replace it with a 3mm lens that faces the LED hole on the rear of the housing. The stock LED is too small to be swapped with a brighter one so I choose the lensed LED option instead.
Excalibur:
Relocated 3-mm LED to the back of the frame.
Halo:
I used to perform this LED mod to Halo boards, which replaced the stock worthless LED with superbright ones in 3-mm or 5-mm lenses. I don't offer this mod anymore (nor do I offer the plexiglass backplates) but you can always try doing it yourself.
This mod used a 5-mm green LED for the idle, and a 5-mm blue LED for the other color...
This version used the same 5-mm LEDs except both of them were blue...
Draxxus Pulse:
Similar mod to the one above.