ya I enjoyed that trick too, it was the first time I had tried it but it worked really well.. You can get the traces to be really fine though I haven't measured the actual doable resolution
Very cool - what settings did you use, and did you have any issues with the copper underneath being reflective? I was thinking of trying this with a K40 for some simple single-layer designs that don't merit waiting a few weeks for fabrication, but I'm a little worried about how shiny and conductive the underlying copper is.
didnt have any issue with the reflectiveness.. I was using a 75w laser printer. Used the etching settings with 100% power 35% speed. Had to do four passes and then wiped it down with a damp towel