Hey guys, I need to build a simple device that climbs a length of string (about 2 metres) without any support from above, and with energy from only the descend of a 200g mass. Speed is of importance. I have considered using two pieces of gears secured onto the string with rubber bands tieing the middles of the gears together. and then, wind the middle part of the gears with strings and attach a mass to the strings. when the mass is allowed to drop, it will give the gears rotational energy and climb up the string, using frictional forces. I am wondering if this could work? How can I improve it if it does, and how can I change it if it doesn't? New ideas are also welcome! Thanks!