This kind of spiral works pretty good at speeding up the marble, but not too fast. Several marbles can all go in a tight row into this spiral and come out rolling faster. As the marble get closer to the bottom, they bunch up and their colors blend until they shoot out the track leading from the bottom. The spiral is about 8" across at the top and is about 5" tall. TIG welded stainless steel. This spiral belongs to sculpture #64. Click for bigger picture.