Hi, Robin! When you say 'relief print', do you mean as in 'woodblock print'?
If that's so, I know one former member had success using a laser cutter to burn the lines into the surface of a woodblock instead, using a dither setting to take down the negative areas. While I'm not an expert here, let me know off the list if you'd like more details and I'll pass along what I do know. Or I'll be in this Friday from 7 PM onward--we have a lino block made with a similar technique, and I believe I have a print pulled from a woodblock made this way.
Kevin F.