White on black doesn't work quite as well as black on white but the base artwork is good enough to cover it. The leetro controller doesn't really do greyscale, it's only capable of on/off engraving so this was done using a halftone image. The artwork was prepared in Paint.net before engraving. I'm working on a greyscale engraving system for my Whitetooth but it's slow going with all my other distractions. You can see how the darker border in the background does actually show up a little. This image would probably benefit from some outlining on the hammers.