tweeter mounting

hi, on my componots the tweeter is a 1 inch tweeter but with the housing it comes to be 2 in diameter. because of the size of it i only have room to mount it in my door. now it is the type where the back part is threaded and it comes with a thing that you twist on it to tightin it place. now how do i put a 2 inch hole in my door? and my door is plastic.

the easiest way is wit a hole saw, it's a round saw blade that fits into your drill. You can get them in all different sizes at any hardware store.