I found that this idea with spike tunnel is VERY useful but I wonder if you can do something that the spike bolls can moving from one side to another , like you have shown to us in the funbelts1 level the moving spike bolls, but it is possible that they will return or they will move around???
When I put this moving spike bolls to my level, they passed only one time and I want theme to passing all the time (Itryied sucker tube but it didn't work)