I have used etching too for the making of brass dial plates but other correspondents are right about it being difficult to get a wide range of depths and a consistent appearance.
In fact the technique is so variable that last time I went to an etch-engineering firm who specialize in the manufacture of parts by etching. This was so succesful that I'd never try it myself again. The result was wonderful. I prepared a twice full size image using a laser printer, printing on six sheets of A4 , which I then stuck together. The result was photographed and etched onto a square brass plate. Although I didn't ask for it I believe they also could have filled the lines had I wanted that, though they said they would have used more undercutting in the etch process had I needed that. The cost wasn't high - the machining of the gnomon from solid cost three times as much!
