The performer shows a cardboard tube to the audience. He then unrolls the tube by pulling on the middle flaps and the tube flattens to a flat piece of cardboard and three different colored silks fall out. The audience can see that the tube is now empty. He then rolls the tube back up and picks up a small white ball. He then explains to the audience that this is a "Rainbow Tube" and when he places a white ball in the top of the tube, the ball will come out of the bottom of the tube a different color. He then places the white ball into the top of the tube and when it comes out of the bottom of the tube it is still white. "Oh, that's right" he says, "I forgot to add the color". He then reaches over and places a small orange silk into the tube first, then places the white ball into the tube again. This time the ball comes out the bottom of the tube and it is orange! He then pulls on the flaps of the tube and opens the tube to show that the tube is empty again. He then places a blue silk into the tube followed by another white ball, and when it comes out the bottom of the tube, the ball is blue! He then repeats this two more times with a yellow and then a red silk. When the white balls emerge from the bottom they too are colored yellow and red. At the end, or anytime during the course of the routine the tube can be shown empty. Great to use with audience participation. You can use up to three assistants from the audience with this trick by having the first one hold a clear cup with the white balls in it, the second one can hold the three colored silks and the third one can hold an empty clear cup at the bottom of the tube to catch the colored balls that come out.