I've got friend who does aircraft modelling and he does his own photoetching. He got some fancy paper from an electronics store that I believe is used for etching circuit boards, draws out the parts on CAD, prints it to the paper which then irons on to the chosen material and then he etches it away. It looks pretty good too, I was going to make some brake discs for my Le Mans entry kit this way. I'll find out what the paper is and what chemicals he uses and let you all know soon.