One other note about fillet size - it is really pretty easy to underestimate how much of a model a particular fillet size is going to consume when the model is made up of some narrow or concave type areas.

For example, here I've applied a fillet of radius 3 to your shape, by using Edit/Separate on the model to break it into individual surfaces, and then picking the inside scalloped area and then outside sphere surface. This does the surface/surface fillet operation instead of the edge-based one.



This is the same radius fillet as the little fillet pieces on the original shape around the eyes! But since there is a sort of narrow pointy area in the scalloped out shape, a fillet of that radius consumes quite a lot of the shape before it will fit, this would include eating up those eyeball parts entirely.

So it can be pretty easy to run into this problem where you are asking for a fillet that simply won't fit in the model at all.

That's why it can be a good idea to go down really pretty small if the size that you first try does not work.

- Michael