The form is created with a loft of two splines for the top, and blend of two circles for the handle.
The Surface and Pattern
Surfaces are divided by U and V with Rectangular Checkerboard creating trapezoidal modules.
The curtain pattern family has a reporting parameter D which measures the module width when the surface is divided. Simply making the radius of the ring R equal to D, the ring can change in size with the module size changes along the surface.