After looking at the dye ingredients, I decided to try using natural ingredients. This way Carter could really help out with it, worry free.
I rummaged through our clothes and found two shirts to use. We tried out the fun marble sphere pattern shown in the book for Carter's shirt and the pleated stripe pattern for mine. Carter helped place the marbles inside the shirt and I cinched the fabric over the marbles using rubber bands. Carter had a fabulous time just playing with the big bag of rubber bands, as well!
After some research I found a juice concentrate dye recipe. I very rarely drink juice, so we had some in the freezer to use. Before I turned the stove on of course....I had Carter pour in the water and frozen juice-cranberry/cherry into a pan. I boiled the juice and then let it sit to cool. Once the dye mixture had cooled down, I placed his shirt in a bowl in the sink and let Carter pour the dye over the shirt until it was completely covered. We let it sit for hours.
Then I rinsed it out with cold water and hung it up to dry. I also repeated the process with my shirt using spices, which seemed to work better than the juice (however, I would choose a different color next time). It seems like we would need to practice and experiment more with the natural dye recipe and process to become good at it. It was fun though!