The exposure rig I've used forever is an overhead-suspended light rig containing 2 500 watt halogen units with the glass removed from each. The bulbs in the units are like 8 inches apart. See attached pic of it hanging in-place above the table I use to expose the screens and print on.
I had someone recently tell me that I need to ditch one of the lights because with 2 sources, there's a greater chance of light undercutting when exposing.
What say you all?