There are a few requirements that need to be met to do relief-carving with the laser. The first is having a CO2 laser that is capable of varying raster power based on grayscale color value and the software in the print driver that controls this. Secondly, a specialized drawing where grayscale color value represents depth is required. Finally, good results won’t be possible without an appropriate carving material, like hardwoods or thick, opaque cast acrylic.
—Jim Puentes, COOLaserCraft