http://FantasticContraption.com/?levelId=28346
(This idea was taken off of the FC forums.)
The idea behind this map is simple. Two or more players create contraptions on the outside of the yellow posts. The ball is in the middle. The concept is that each player's contraption battles it out to get the ball to the opponents goal.
Instructions
The first player loads up the map (link above) and creates their contraption to one side. This player saves their contraption and posts the
contraption link.
Subsequent players load up the posted contraption on the map. This player then creates their contraption on the opposite side. This player saves their contraption and posts the contraption link.
If there are more than two players, the next player in line removes the losing contraption from the map and adds their contraption. Continue as needed.