There's an Instructable on making PCB's using a laser engraver, sort of like a reverse toner transfer:
http://www.instructables.com/id/Printed ... ser-Cutte/
Instead of trying to burn off the copper, the laser burns off black spray paint applied to the copper-- clever! It then needs to be etched, but it should allow for thinner traces than toner transfer. And if the copper clad is nice and rectangular, it should be possible to do a double-sided board with pretty high precision, using a cutout to position the board.