I’m sure there are many ways to accomplish this. Here’s one possibility.
SHIFT + “A” Add Mesh > Circle with 64 vertices (Top View “7”).
TAB into Edit Mode press “E” and “S” Extrude Scale three times.
Select this vertex and press SHIFT + V and slide it until the corresponding edge is parallel to the X Axis.
Repeat for this vertex until the corresponding edge is parallel to the Y Axis.
Select 3/4 of the vertices and press “X” choose Vertices from the drop down menu to delete them.
Add a Mirror Modifier check off “Y” “Z” (“X” is checked by default). Also add a Subdivision Surface Modifier (Change the View to 2). Tab into Object Mode and select Smooth Shading then Tab back into Edit Mode.
Add two Loop Cuts (CTRL + “R”).
Select the following ten interior faces and press “X” and select Faces from the drop down menu to delete them.
Press “A” to select all and press “E” to extrude them up.
Select the following interior faces and press “X” to delete them.
Check off Clipping in the Mirror Modifier.
Select these faces and press “E” to Extrude them up.
DE-Select these six faces then press “E” to extrude the remaining faces up again.
Tighten up some of the edges with Loop Cuts.