How to create a custom round icon button similar to FloatingActionButton

While FloatingActionButton always comes in handy when making a prominent icon button, sometimes we want to customize the button to suit our needs.For this we can use RawMaterialButton to get the customization we want.An example is given below:-

RawMaterialButton(
  onPressed: () {},
  elevation: 2.0,
  fillColor: Colors.yellow[300],
  child: Icon(
    Icons.play_arrow,
    size: 140.0,
  ),
  shape: CircleBorder(),
)