Well, it's not that custom (and it's a bad pic), but my G21 has a Lasermax, Ghost Rocket connector kit, and a 25 cent trigger job; and it actually has a decent trigger feel, for a Glock, but it still looks like most any other generic Glock.
The story behind it is that I bought my wife a Lasermax for her 92F, and she reciprocated for my G21. That was ten years ago. Just recently, I decided to attempt to improve the trigger feel, and went with the Ghost connector. During the process of installing the connector, I ran across a youtube video for smoothing up the trigger feel, and decided to give it a try; and, both work well.
Everything so far is reversible except for the polishing, and I still have all the original parts so I can go back to factory configuration at any time, but I like it in this configuration better, and it's still completely reliable, as a Glock should be.