Hi Jez,

Actually, that would be "printing" the negative. I was thinking along the lines of printing the positive directly onto the FR-4 (or whatever substrate you needed, e.g. PTFE, Kapton, etc.).

It seems to me that a conductive liquid could replace the ink, even if it only served as the base to which subsequent plating could occur.

They have to treat holes with something before plating them. Why not put that stuff into an inkjet cartridge and print your trace pattern directly onto your substrate of choice?

Anyway, it's a thought.

Joe