If you have the room to work in, a sabre saw will work just fine....it will cut a fairly small radius circle, if you don't care what it looks like, use a sawzall, the hole saw in the electric drill will leave a very nice looking, neat hole.....the down side of the hole saw is that if it catches or binds in the hole, it will break your wrist. The larges hole saw that *I* will use in a drill is 4 inches, and I do that kind of stuff for a living.