Motion Trail for an animated object

Hello, I’m working on a project to make a physics demonstration, and I need a trail to appear behind a moving object.

I have been trying several ways to do this…

I am animating the object using a bezier-curve, and so I would basically like the curve to appear behind the object. I tried using a build modifier on the curve, but I couldn’t find an easy way to animate the build modifier to match with the position of the moving object, so it would get ahead and behind occasionally. Is there some easier way to make the curve appear? I feel that there should be some type of modifier, similar to the follow path, so that I can use the same ipo curve that I used to animate the object to build the curve.

I am also thinking about deforming a second curve with the path, and then scaling that curve up accordingly… would this be possible?

Basically, I just want a solid trail to appear behind the object that I am animating.

Thanks in advance for any advice or suggestions you can offer!

-Andrew Miller