The Acer K138ST is a unique piece of work. It's a short-throw projector aimed at the sort of person who brings their projector with them at all times. It has built-in speakers, extremely bright lights inside, and is ready to roll with ambient light sensing to contribute to smart adjustments at any time. It's small enough to fit in your backpack if you really want to be a traveling projectionist. This little beast is just one of three new projectors revealed by Acer this week in New York City.