I build this three foot slider potentiometer and it sort of works but there were a lot of design flaws. I think I should got back to my original concept of using a touch potentiometer and maybe cover the mylar with one of the cool plastic sheets from Plastic Land. My biggest stupidest flaw was using a small nail head embedded in the bottom of the slider to connect the mylar and copper. This kept getting stuck in grooves that were left from my incomplete sanding job and then tearing up the mylar. Having it be a touch potentiometer will get rid of this problem. The downside to having it be a touch potentiometer is that the user will be able to jump all over the movie, so there might be no continuity in the images if they just jump around instead of pulling across the sensor and keeping the images coming continuously. It’s possible that people will feel compelled to do this anyway, to see the story unfold in chronological time.