What finish does the kit already have? That will make a bit difference on how the engraving looks.
A diamond bit or other mechanical engraving method should work fine. You could always to a mechanical etching with a color fill that complements the blank.
The greatest majority of laser engravers use CO2 lasers (gas tube or RF pumped) that operate at 10.6 nm. Those will cut wood, acrylic, most kinds of fabric, and etch things like glass because those materials will absorb the energy from it.
Metal does not absorb that wavelength, it reflects it, so it won't cut. That said, there is one metal whose name escapes me that you can cut with a CO2 laser. Additionally, with enough power you can cut it, but you are talking about kiloWatts for metal, where the engravers are generally in the 30-60 Watt range. I have seen one rated as high as 120W for sale, but I don't think it was actually that high. CO2 gas lasers get thier power by length, and there was no dimension long enough on that system to generate the rated power.