Re-melt, re-shape, or clean up with a heat gun.

A heat gun can be used to get rid of those little strings you sometimes get on your work (usually created when pulling the 3Doodler away while extruding). One pass with a heat gun and they shrivel right up to nothing! It can also be used to gently remelt pieces of PLA, which can then be reshaped long after they were first Doodled.