Use a ball and foil or a marble to make a perfect sphere.

Doodle a ball using a spherical object as a template! Cover the spherical object in foil and Doodle over half of it; then remove the Doodle and and another half. Take that second piece off and join your two halves together with the 3Doodler. This way you won't trap your spherical object inside your Doodle. Once you have a complete Doodled sphere, you can add details to it any way you want.