The pencil tool in Adobe Illustrator is great when paired with a tablet.
You can use it to manipulate existing paths, but make sure when manipulating existing paths you start and end on the path that is being manipulated.
You can even make CLOSED freeform shapes with it, but its a little tricky in my opinion, as you have to start drawing the freeform shape then press option or alt just before you finish the path.
Hope this helps:)