It was a cool idea, but unfortunately, it won't work. If you use the laser cutter to cut all the way down to metal, the metal will reflect the laser back at the mechanism... which would not be good.
For attempt two I'll use a more tried and true technique. Basically, I'll use a laser printer to make an image on a transparency, then place it on my metal and iron it, melting the toner again and transferring it to the surface of the metal. That should be sufficient to keep the acid from eating those spots, and give me the same effect... though it adds a step and probably won't be QUITE as clear.