I can etch onto anodized aluminum, which burns the dye out of the anodizing leaving it white. The laser won't cut metals. Plexiglass I do all the time. It's my favorite material. I can easily cut up to 3/16" plexiglass and can etch it very nicely. Once etched, you can either just peel the paper off or you can fill the etching with paint. I can also peel off the paper and do a light frost etch. I can even do it on both sides for a multi-layer effect.
As my work log on my current system progresses, you will start seeing some multi-layered etching with lighting.