Check out the Vector Paint and Light Storm tutorials from Bill O'Neil. They are over 10 years old, so you will have to update some things, paint for vector paint.
Or you could use a particle emitter like Andrew Kramer does here: 3D Stroke Effect
Johnny Cuevas, Editor
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.