I’m with @zeHamish, sci-fi would be my suggestion. Maybe add some LEDs, electroluminescent wire, maybe some pew-pew noises haha.
I personally like paint jobs with black and another colour. Black and white, black and blue, black and red, black and gold… so many options.
I’ve always thought that a vector could be made into a badass sci-fi or steampunk style pistol when you removed the stock + barrel extensions.
I like to surf around on Google Images a lot haha. Just search something along these lines:
“modified kriss vector”
“custom kriss vector”
“kriss vector skin”
I also recommend looking on imfdb.org to find where the vector has appeared in popular culture, then looking those places up separately to see what the designers did for that game/movie. When I was painting my SCAR, I found the paint job from Kingsman: The Secret Service, which has a cool white and black theme.
Finding an outline picture of the vector, and using the fill bucket in Paint could also be of some use.
Maybe even paint a badass name for it on the side, something Borderlands-esque. A bit nerdy, but a reference to mathematical vectors, a quantity with a magnitude and direction, would be cool too (an arrow that says “direction” on it near the barrel, write “MAG-nitude” on the mag, idk.
My final suggestion would be to look at little things from video games e.g. CoD has dog tags and keyring style things that hang from the front or side of it.
Yes, I am childish. I think the whole gel blasting community can lose its sense of humour sometimes though, so I would say just go crazy and have fun with it.