Freddy, I don't know what your interest level is, but it's enjoyable to do some experimentation for me.
A base coat of silver (Eastwood has a pretty good deal on it) and then make your own colors and hues by mixing (for example) dry pearls, available in a wide variety of special effects and colors and shoot that over the base silver, followed by candy, (below) or a just a clear coat.
To this, or independent of this, you can use "candy concentrates" and tint your clear and shoot it over the base and come up with a truly individual paint job.
With actual flakes and/or pearls, you want to limit the size to your gun. I've found the replacement tips for paint guns are about the same cost of a new gun. Just tossing this out there, if you (or anyone else) would like to experiment. For the most part, it's pretty easy to do, but tedious enough to feel good about creating.
That little engine looks beautiful!