The typical engraving stock used is two-ply flexible plastic, which typically has a thin cap layer and base core material. The cap layer becomes the background, and as the cutter cuts through the cap to expose the core, that becomes the engraved image color. Available in an array of cap and core colors – the most standard colors are white, black, red, and blue.
Metals are also a popular substrate for rotary as most cannot be laser engraved without a marking agent. Common items to engrave are brass, aluminum, steel, and stainless steel. Free cutting brass is pretty easy to engrave, aluminum tends to gum up, and steel and stainless are hard metals. The harder metals take a bit of practice to get right.
—Quality One Engravers
