How to make a custom shape?

I know how to draw shapes such as circles, rectangles and other stuff, but what would be the best way to draw groups of shapes as one shape object?

I currently have a class that has three methods, two return rectangle shapes and one that returns a Pen.
My WinForm uses this data to draw a rectangle with another rectangle inside it, and uses the pen as its Pen.

What would be a better way to structure this?