What is the best way to create a doughnut shape 3D object.?
The manual way would be to draw a circle, without face, to define the path. Then draw another circle, with face this time, perpendicular to the first circle and use follow me to extrude the second circle along the path of the first.
Here is one video of one way to do that:
Alternatively, you can download “Shapes” from Extension Warehouse and you will have access to a nice set of geometric primitives:
http://extensions.sketchup.com/en/content/shapes