Design and build electronic movement system (sideways movement)

Hi, I'm an absolute layman with electronics however I wish to design something like this [login to view URL] to incorporate into a sideways movement into the back of a thin photo frame . Alternatively: [login to view URL] It has to be as thin as possible so as not to protrude too much when mounted on the back of the frame. I need this for an art project and the components need to be as small and slim as possible. The track needs to be at no more than 8" long for the sideways movement. Further, the movement needs to continuous back and forth motion, minimal pausing between direction changes. It needs to last long on a AA battery. If someone can design and ship it to me even better!