How to use the manipulators in the Surface Fillet tool to build a variable radius fillet.

Choose Surfaces > Multi-Surface Fillet > Surface Fillet to show the fillet control window.

In the control window, set Construction Type to Radius and check on Variable Fillets.

You can add several radius manipulators along the length of the fillet and assign them different radius values.

To...	Do This
Add a new radius manipulator	Click a point on the blue line running along the fillet surface.
Select a manipulator.	Click the manipulator.
Change the radius of the selected manipulator.	Drag the .
Move the selected manipulator along the surface.	Drag the .
Remove a manipulator.	Hold and click the manipulator.