I work with PCB's a lot, directly in the creation process.
Simply etching out the copper (I am usually using a LPKF mill) is generally not enough to make the board usable to the general public (or pleasant for yourself). Soldermask is generally applied over the copper (Solder-mask over copper, or SMOC) which is done via application of a thin paint that is cured selectively with a UV positive or negative image.
