Use a micrometer to measure the spacer. I'd recommend turning the saws by hand and scraping through the copper. Rotating them with power requires a guard, carbide is brittle and can break apart. Even some modern watch parts in mechanical watches are etched. Film has a resolution around 8000 lines per inch or 16000 dpi.
Lasers can take things down to the wavelengths of light.
On a more practical nature, there are LaserToner transfer systems. I have had mixed luck with these. What happens is laser ink is plastic and melts at low temperature. The transfer is a sheet of water soluble glue. This is an electrostatic process.