The "kit" isn't needed - just a small bottle of Gold paint from a Train/Airplane Hobby Shop, a few tissues/Kleenex, a wooden toothpick, and some lacquer thinner.
Work on only one area/surface at a time.
1) Degrease the roll-stamped "engraving" with laq thinner on a rag or tissue paper by flowing it on & rubbing lightly, then let the area air dry. (Drying occurs in a few mins)
2) Mix the Gold paint thoroughly by shaking the bottle vigorously for a minute or two, then dip one end of the toothpick into the paint to pick up a blob of paint, to fill the stamping/engraving fully. (don't worry about overfill/overrun at this point)
3) Let the paint start to "dry" for only a few minutes, before starting to LIGHTLY wipe off the overfill.
4) LIGHTLY dampen a tissue with laq thinner, and with the damp tissue wrapped around a fingertip, start to lightly wipe the gold paint off the top surface areas in/around the stamping/engraving.
If you press too hard, or wipe in the same direction as a groove/line, the soft tissue will get down into the stamping/engraving & remove the Gold paint from where you want it to stay.
There's plenty of time, to make a pass or two.
When everything you want filled is done, let the Gold paint dry overnite before applying anything to the painted area.
(Sometimes you can carefully oil the surrounding areas with a tissue wrapped around a fingertip, dipped in a bit of oil, & being careful not to oil the paint)
The Gold paint will gradually wear off if it's constantly touched, hit with cleaning fluids and/or oil.
Anyone who likes the look can easily enjoy it at low cost, and just as easily remove it if they change their mind, or decide to sell the gun to someone who doesn't like the look..