Using a hole saw is the fastest and easiest way to create a hole up to several inches in diameter. A hole saw has three parts: an arbor that attaches to a standard drill, a pilot bit, and the hole saw itself. The saw will fit into almost any drill but one that will accommodate a 3/8" shaft is best.
A common problem when using a hole saw is that it tends to tear out as the saw exits on the opposite side. To prevent this from happening, begin drilling from the first side as usual, but before the saw goes all the way through, go around and finish the hole from the other side. The result is a clean hole on both sides.