Concepted out Hackaday contest entry, a gravity powered curtain opener/closer. Designed four simple components in 3D that allow weights tied to the center hole of the -005 components to sequentially slide out of a carriage assembly and thereby draw the curtains opened and closed. The -007 slider is connected either to some servo or a bimetallic strip. As it slides inside the -008 channel, at either extreme, it makes an opening for the next -005 sliding component to fall by gravity out of the carriage. A frame will be necessary to hold the -008 and -006 components in relative position, as well as the motion input system.