On the video I found, they used spray paint to give a tie dye effect. I wasn't sure how that would wash up, or if it would be stiff; so I used a spray on fabric dye I found at Hobby Lobby called Simply Spray.
This was such a fun and simple project that the kids literally didn't need any help doing. I showed them once how to twirl the shirt up; and then they took off with it.
I love how each shirt looked so different based on the colors they used and how much they twisted the shirt.
The only problem with the Simply Spray was - these shirts faded A LOT! The colors kind of bleed and none of the lines look as crisp now as they did on the first day. I did wait the 72 hours to wash like the directions said; however - I did not pre-wash the shirts and I probably should have.