I remember making plates for a pad printer long ago. Back then we had a second sheet we'd expose that had dots all over it. I called it the "Gravure" sheet, but that's probably wrong. It was supposed to break up large open areas with pits for the ink to get sucked out of in a more controlled fashion.
It was an inexpensive personal home tanning unit that I build the box around. It had four UV bulbs. But any UV bulbs would work. This is a similar method to making a screen printing exposure unit and there is much information online on those, too.
