Shorts (or shirt, or pants, or pants, or skirt, or whatever else you want to dye)
Dye (I used this, but any type of dye suitable for tie dying will work just fine. You can generally find the Tulip kits and individual dyes in craft stores and some big box retailers.)
Special note about dyes: Rit Dye is popular, but I would not recommend it for this particular tutorial, or any tie dying in general. I learned this the hard way. If you do choose to use it you must follow the package instructions versus my instructions here.
Here are the shorts I am transforming. You want to start with something white, or very light in color for best results.