Wood and leather are easily engraved with a laser. They can also be laser cut, with thickness up to 3/8" depending on the type of wood.
The laser will surface etch glass, and give it a frosted look and texture. Surprisingly, cheap glass works best with the laser. Leaded glass will not work with the laser because the lead in the glass will expand and crack the glass.
The laser will not remove material from metals. Steel and aluminum can be marked using a special bonding agent. It will look like black silk screen and is solvent and wear resistant. The metal must be free of any coatings prior to marking. Anodized aluminum can be marked without the bonding agent. The laser bleaches the color from the anodizing, and will leave a white design. This works best on darker colors of anodizing.
Plastic and acrylic are easily engraved or cut with a laser. PVC based plastics should NOT be engraved or laser cut. They put out toxic and corrosive gases when subjected to high heat, which are a health and equipment hazard.
Stone and tile can be surfaced etched the same as glass. Dark solid colors work best, and sometimes a paint fill is necessary to improve the contrast. For a deeper cut on stone, sandblasting is recommended.
Due to the nature of these metals and the specific frequency of a CO2 laser, brass, pewter, silver and gold cannot be engraved or marked. For jewelry it is recommended to go to a jeweler.