As a culmination project for the CSU Sophomore Design Class(ME202) students were allowed to select a group of 3-5 people, design, build and use in competition with the rest of the class a device that travelled down a 1/4" wire. Ten feet of wire seperated the started point for each team, each team was given 1 foot of wire for their device to mount and start on at the beginning of the competition. The device that was furthest down the wire when all devices came to rest was the winner.

Our approach after many sessions of brainstorming, concept sketches on bar napkins, revision and after revision, number crunching, was a pentagraph ("scissor jack") device.

This youtube video shows the completed device during testing on a mock competition stand built in my garage(click to play):

http://www.youtube.com/watch?v=p4yMMSe4RN0

This is the modeled and assembled part, used to verify compressed and extended length: