Controlling a circular magnetic field with microcontroller
To get the ring shape, you will need to use a magnetic trap, the proof of concept of this would be to have 2 coils in the shape you want (the circle), spaced apart by about 1.4x how wide you want the circle to be.

To get the spikes, you will need magnetic traps aswell, though this time it can just be a single coil in the shape of the spikes, this likely means you will have to settle for radius out shapes for hands on the clock, you would turn on these coils in sequence to move the hands. 

The amount of current you will need to run through the wires will also be fairly high, you can reduce it by having more turns, and likely will only work well while flat, in a vertical situation against gravity the control scheme would get quite difficult to make it a somewhat even thickness, 


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To best explain the image, the ferrofluid will gather at the pole of a magnet, 2 coils with opposing current flow will make a consistent pole between them that is attracting it into that shape, you need 2 coils here as you want the entire ring shape, 

This would be the point in the 2b diagram where all of the field lines are bunched up tightly,

For the hands as you just need the fluid trapped inside the profile of the coil, so a single coil can be used.