Pencil Tool: Use to draw a curve or shape anywhere in the simulation window. In the Properties Box, you can change the color of the curve or lock the position of the curve.

If you use the pencil tool to draw a curve on top of another object, the curve will remain connected to that object. Thus, if you move the object around, the curve will move with it. If you delete the object, the curve will also disappear. The curve will not change size or rotate with the object.

Also, you can move the curve off the object, but you cannot disconnect it! To understand what this means, try the following. Draw a black curve on a red rectangle. Then move the curve off the rectangle. Finally, move the rectangle around the simulation window. You will see that the curve moves with the rectangle while always keeping the same position relative to the rectangle! The only way to "disconnect" the curve is to delete it and draw it again, this time off the rectangle.