Making the hub is easy. It's simply a cylinder. Perform the following steps:
Press 7 on the NumPad to get the Top view.
Press the Tab key to get into Object Mode.
Press Shift + A, and then create a cylinder from the Mesh menu.
In the Add Cylinder subpanel in the lower half of Tool Shelf, set the number of Vertices to 18. Set the Cap Fill Type to Triangle Fan.
Press S, 0.25, and Enter.
Press M, 2, and Enter to move the hub to Layer 2.