-I started from cylinder, removed top and bottom, selected every other and scaled them down (scale only in X and Y by hit S to scale and then SHIFT+Z to remove Z axis from scaling so it will remain flat)
-Then I bevel it.
-select the outside (you can select first and second and then pres CTRL+SHIFT+PLUS on num pad so the selection will repeat) and bevel again
-Then just select the top vertexes and move them up to desired height scale a little as the top is smaller then the bottom. Use another object for top and bottom or as I did extrude it and use LoopTools > make circle.