Using guttering, downpipes, canes, chairs, tables etc. each team constructs a course from one end of the hall to the other and then race ping pong balls down the course.
House guttering and downpipes, canes, rubber bands, ping pong balls, chairs, tables
Give each team the same equipment and tell them to get the balls from one end of the hall to the other. Can also be played outside and challenge them to get the ball to roll the furthest. You may wish a rule where they can't touch the course during the race. Then again you may want to leave out this rule and award extra points for the team that has the initiative to reconstruct the course as the ball is rolling down the guttering using bits from the start of the course to add on to the end!