This guy is using a UV laser to remove paint on a PCB.
http://gabuleu.blogspot.com/
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Wednesday, January 06, 2016 5:03 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: 3-D printer resist application? (was: Re: [Homebrew_PCBs] Anyone milling PCBs?)
I have used this technique with spray cans of paint, and it works fine. The biggest problem I had was the lines cut were a bit narrow. At the time I had access to a big CNC system with a Q-switched YAG laser, but since I retired that is no longer the case.
Bob