Everything important in this world is either circular or oval in shape. A fact that no one can ignore. So most of the time that effects our designs. It just shows. things fall into place. 
This is full on vector. Everything done in Adobe Illustrator. And the tools I've used are Elipse tool, Line tool, the Gradient tool and ofcourse the Pen tool. As you can see Every object has a shade of grey. Lighter or Darker. My personal work. I enjoyed doing it.