I really only have an idea of what i'm looking for but think of this, http://www.horizonplatforms.co.uk/images/D/50ES.JPG , but very small. It doesn't have to work the same as that mechanically, but i need something that can open and close a sliding glass door. I am going to be using an arduino to detect a gesture, and once detected open the glass door. my idea was to have something similair to the img above, but small enough to fit in the rails of the sliding door, and has enough length to push it open. Ideas?