Completed my first tye dye cake this weekend and was very happy with it. I was scared I wouldn't like the effect the first time and have to scrap all the fondant but it worked!
http://cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1813488
I just rolled out several "snakes" of each color, pinched some over onto the next color, wound all into a spiral and rolled out. I was especially happy with the bottom tier.
!
Great job. I was just about to start searching for tie died tips. Thanks for the details on how to get the effect.
As someone who is about to turn 50, I give it my enthusiastic approval!! 
I knew it could be achieved!!! I knew it!!!
That cake is gorgeous!! I attempted to do a cake like that a few months ago, and everytime I rolled it out.. at first it would seperate into its individual colors...then about the third time rolling it out, it turned brown on me!! 
Oh I knew it would be gorgeous. YEAH !!! I am going to have to attempt it again using your method to combine the fondant.
Quote by @%username% on %date%
%body%