The plan produces what is essentially a ''barber pole'' spinning slowly from a kite line (if colours red and white is used). Where the Twisty Tube Tail consists of essentually a single bulge spirialling around a kite tube, the double twist is two such bulges spiriling in a double helix. This means that you can cleanly colour the two bulges separately, unlike the original twist tube.
Follow the basic construction details in the Twisty Tube Tail Plan however in this case you will create two strips, each a single solid colour. (IE: #1 .. #4, #5, #5, #5 ... #5, #5, #4 .. #1 ). The end pieces are then attached. Finally the two strips are sewn together down the diagonals (in a spiral down the tube) to complete.
Alternativally, by following the diagram below you can join all the strips in a long rectangular like shape instead of diagonal strips that spiral around the tube. Add the end pieces, then sew the final seam. Note this seam is not straight, as it is in the strip method, but then you don't have the seam spiralling around the tube either.
If like this plan, and/or build one, please mail and let me know what you think. Including any ideas, suggestions or other experiences. That way I can add them to the above so others can read and benefit from your results. :-) Photos especially welcome!
As a variation, replace piece #6 which forms a cone on the tail end of the tube with a white ball. Note that the lower part of piece #7 which forms the flower-head is a `gore' pattern for such a ball. This would make the twist tube look even more like a barber pole.