One of my clients, a chemical engineer, decided to make his own PCB's because U.S. prototype houses were too costly and slow, and offered too old a technology, i.e. inadequate features, too coarse a tolerance on dimensions and registration, and far too large a trace width and clearance. He was often able to fabricate his PCB's to his desired spec's by methods similar, in part, to yours, but ultimately decided to buy a Gerber plotter rather than trying to "squeak by" with a printer to generate his films.

His solution was to order a moderate (250 pcs) quantity of his boards from manufacturers in the PRC, as they were electrically tested while U.S.-made prototypes generally are not, and he found that between the much better yield of useable boards (>>90%) and the considerably lower cost per batch, disregarding the quantity, and much quicker delivery, he was ahead on both cost and quality.

RE